Why are neutral [sterile] female flowers present in inflorescences when they are reproductively incompatible?

Why are neutral [sterile] female flowers present in inflorescences when they are reproductively incompatible?

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

In many compound and special inflorescences like spadix and hypanthodium there are sterile female flowers along with male and female fertile flowers and are often present in between male and female flowers, but what is their need in an inflorescence?

As far as I know inflorescences are meant for perpetuation of a plant's race by pollination of female flowers by the male gametes [pollen grains which bears vegetative and reproductive cells].

I know the infertile female flowers of the spadix inflorescence possess some surface area and this area would get some of the pollen grains which are coming in to the inflorescence, and eventually a sum of pollen grains might go in vain.

What is the need of sterile female flowers when fertile ones are present in it?

Sterile flowers enrich pollination quality by promoting pollen export and import, while limiting the mating costs of geitonogamy associated with large fertile displays.

You are actually looking for this paper: Link:

Sterile flowers increase pollinator attraction and promote female success in the Mediterranean herb Leopoldia comosa

Key Results

The presence of sterile flowers almost tripled pollinator attraction, supplementing the positive effect of the number of fertile flowers on the number of bees approaching inflorescences. Although attracted bees visited more flowers on larger inflorescences, the number visited did not additionally depend on the presence of sterile flowers. The presence of sterile flowers improved all aspects of plant performance, the magnitude of plant benefit being context dependent. During weather favourable to pollinators, the presence of sterile flowers increased pollen deposition on stigmas of young flowers, but this difference was not evident in older flowers, probably because of autonomous self-pollination in poorly visited flowers. Total pollen receipt per stigma decreased with increasing fertile display size. In the population with more pollinators, the presence of sterile flowers increased fruit number but not seed set or mass, whereas in the other population sterile flowers enhanced seeds per fruit, but not fruit production. These contrasts are consistent with dissimilar cross-pollination and autonomous self-pollination, coupled with the strong predispersal inbreeding depression exhibited by L. comosa populations.


A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Magnoliophyta, also called angiosperms). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism for the union of sperm with eggs. Flowers may facilitate outcrossing (fusion of sperm and eggs from different individuals in a population) resulting from cross pollination or allow selfing (fusion of sperm and egg from the same flower) when self-pollination occurs.

There are two types of pollination: self-pollination and cross-pollination. Self-pollination happens when the pollen from the anther is deposited on the stigma of the same flower, or another flower on the same plant. Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination happens in flowers where the stamen and carpel mature at the same time, and are positioned so that the pollen can land on the flower's stigma. This pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators. [1]

Some flowers produce diaspores without fertilization (parthenocarpy). Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds.

In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, and also as objects of romance, ritual, religion, medicine and as a source of food.

Get full journal access for 1 year

All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.

Get time limited or full article access on ReadCube.

All prices are NET prices.

Reproductive Isolation, Prezygotic

Prezygotic Isolation

Reproductive isolation represents a breakdown in the ability to reproduce successfully with sexual partners of another type of organism, and speciation requires a build up of reproductive isolation between diverging types of organism until gene flow is sufficiently rare or ineffective that the entities are considered ‘good species.’ Traditionally this was thought to require complete or near complete cessation of gene flow, though increasingly absolute reproductive isolation is thought to be too stringent a criterion ( Mallet, 1995 Wu, 2001 ). Factors which influence prezygotic isolation are those that come into play before gametes of the different types meet and form zygotes. After this point postzygotic isolation occurs, and this simple classification of categories of reproductive isolation based on pre- and post-gametic fusion has been widely adopted since Dobzhansky originally categorized major factors influencing the origin of species into various ‘reproductive isolating mechanisms’ ( Dobzhansky, 1937 ). However, it is important to appreciate that all factors influencing reproductive isolation act in combination. If cross-matings between males and females of different types are half as likely as within types we say their isolation index (I) is 0.5. If the viability of their offspring is also around 50% these are equally effective barriers to gene flow, and acting together will produce a combined I of 0.75, though prezygotic isolation will have made a greater contribution to the overall isolation only because it occurs first ( Coyne and Orr, 2004 ).


We estimated the extent to which divergence in six important ecological traits (Figure 2) generates extrinsic postzygotic isolation among checkerspot populations adapted to feed on Pedicularis semibarbata and Collinsis torreyi (hereafter referred to as Psem and Ctor, respectively). We do so by comparing the traits and associated fitnesses of two classes of hybrid insects: hybrids between populations adapted to different host plants (different-host hybrids) and hybrids between populations adapted to the same plant (same-host hybrids). This comparison isolates the consequences of divergent host adaptation (affecting only different-host hybrids) from those of genetic drift and other types of local adaptation (affecting both different- and same-host hybrids) [34],[42],[43]. All insects used in our experiments were produced by crossing butterflies from four populations—two adapted to Psem and two adapted to Ctor (Figure 1C). Throughout this article, we refer to particular types of hybrids using two-letter symbols (PP, PC, CP, CC) where the first letter indicates the mother's traditional host and the second letter indicates the father's traditional host. We refer to “pure” insects stemming from crosses within a single population using one-letter symbols (P or C) indicating the population's traditional host. We address each trait and its fitness impacts, below, in the temporal order with which those impacts occur during the life cycle of a hybrid insect.

Early Larval Performance Mediates Weak Asymmetric Isolation

We examined the performance of young hybrid larvae by placing hybrid eggs on naturally growing host plants in the field one day before hatching and then monitoring the growth and survival of the resulting larvae for 10 d. Hybrids were only examined on the host to which their mothers were adapted, and thus on which their mothers would have laid their eggs: CP and CC on Ctor, and PC and PP on Psem. Pure larvae were also included on their traditional hosts for reference: C on Ctor and P on Psem. Same-host hybrids did not differ from the corresponding pure larvae in either growth or survival (CC = C on Ctor, PP = P on Psem Figure S1). Different-host hybrids performed well on Ctor (CP = CC/C for both growth and survival Figure S1A, Table S1). However, on Psem they grew 15%–30% more slowly (PC<PP/P for growth PC = PP/P for survival Figure S1B, Table S2). The trend for reduced growth on Psem was significant only when predators were excluded (ANOVA p = 0.0001 and 0.18 in the absence and presence of predators, respectively Table S2), probably because our predator exclusion technique allowed us to control for variation in the quality of individual Psem plants (see Methods). In summary, hybrids between populations adapted to Psem and Ctor were at a slight disadvantage on one of the two host plants. This weak, asymmetric effect is likely to be extrinsic since it disappeared on a third host (see section entitled “Different-Host Hybrids Are Not Intrinsically Unfit”).

Intermediate Larval Foraging Height Mediates Moderate Isolation

Different-host hybrid larvae forage at intermediate heights.

Different-host hybrid larvae foraged at intermediate heights relative to larvae with two parents adapted to the same host. On Ctor, the mean positions of first instar CP and PC larvae were slightly lower than those of CC and C larvae, and substantially higher than those of P and PP larvae (Figure 3A ANOVA p<0.0001). The difference between CP/PC and P/PP was replicated when second instar larvae were tested on Psem (Figure 3B ANOVA p<0.0001). On neither host did we observe a significant difference between reciprocal different-host hybrids (CP = PC) or between pure larvae and the corresponding same-host hybrids (C = CC, P = PP).


Gynodioecy has long drawn biologist’s attention to the question how females are maintained in the population. Theoretically, a female advantage is necessary for the maintenance of gynodioecy. In the study, we found that floral traits significantly differed between two sexual morphs in the gynodioecious S. pratensis. Sexual divergence in flower size conferred female individuals an advantage in pollen deposition (i.e. receiving pollen) over the hermaphrodites, because relatively smaller flowers of the female’s fit better to the pollinators. However, the females just gained a slightly higher fitness than the hermaphrodites due to their intrinsic disadvantage in pollen availability during pollination that is, pollen limitation could be one of the main reasons for the weak difference in female fitness between two sexual morphs. Therefore, it was predictable that the female advantage in fitness varied with population dynamics (e.g. sex ratio) and pollinator’s activity. Floral traits overall underwent strong selection in the gynodioecious population, with flower size and stigma position subject to disruptive selection. Flower production tended to be under correlational selection with floral structural traits, implying that many more flowers in a large plant could not be transformed into the advantage in fitness unless the flower construction mechanically matched pollinators well (i.e. efficient in pollination). In conclusion, the pollinator-mediated selection likely played an important role in the evolution and maintenance of sexual dimorphism in the gynodioecious S. pratensis, and the sex-divergent mechanical interaction with pollinator served as a mechanism by which female individuals, with an advantage in pollen deposition efficiency, were maintained in the gynodioecious population.

Pollination and floral scent differentiation in species of the Philodendron bipinnatifidum complex (Araceae)

The Philodendron bipinnatifidum complex of Philodendron subgenus Meconostigma may comprise four species, which because of only slight and not very distinct morphological differences are not all unanimously recognized as good species. To find out whether these species are reproductively isolated, we studied the flowering rhythm, thermogenesis and pollination biology of three species of this complex, namely of P. bipinnatifidum, P. aff. bipinnatifidum (provisionally named “P. form selloum”) and P. mello-barretoanum in Brazil. Of the first two mentioned taxa, floral scent was collected and scent compounds were identified by GC–MS. The results showed that the coastal forest species P. bipinnatifidum has a two-, or three-night flowering rhythm, with the pistillate stage in the first night and the staminate stage lasting the second and sometimes also the third night. Strong thermogenesis with extended heating periods of several hours during the first part of the usual two subsequent nights and the maximum temperatures of up to 40 °C absolute heating of the spadices occurred in the pistillate and staminate stages. Concomitant with the heating periods, relatively low amounts of principally (Z)-2-pentenyl acetate and (Z)-jasmone were emitted by both the pistillate and staminate stage inflorescences. The dynastid scarab beetle Cyclocephala variolosa was the only pollinator attracted. The upland forest P. form selloum always had a two-night flowering rhythm with the pistillate stage in the first and the staminate stage in the subsequent night. This world-record holder of thermogenesis can heat up to the remarkable 45 °C during a relatively short period in the evening of the pistillate stage. During the thermogenic period, enormous amounts of principally 4-methoxystyrene and 3,4-dimethoxystyrene were produced and which could attract a large number of female and male individuals of the dynastid scarab beetle Erioscelis emarginata. In the staminate stage of P. form selloum, temperature elevation is significantly lower and the scent compounds are different from the pistillate stage. The cerrado biome species P. mello-barretoanum has a flowering rhythm similar to P. form selloum, reaching a maximum heating of about 40 °C during the pistillate stage. The sole pollinator attracted was Cyclocephala atricapilla. The differences observed and analyzed among the taxa, including the flowering rhythm, thermogenic activities, scent compounds emitted, pollinating dynastid scarab beetles attracted, as well as slight morphological differences and apparent geographical exclusiveness noted in these three taxa are strong indicators that P. bipinnatifidum, P. form selloum and P. mello-barretoanum are different enough to be considered good species. The morphological affinities of these species might be a hint that speciation has been a recent event and/or also that reproductive isolation based on different, non-overlapping distribution areas, different scent compounds and different pollinators was effective enough to need further morphological differentiation.

This is a preview of subscription content, access via your institution.

Allopatric Speciation

Divergent speciation events can be categorized as those in which the populations that are separating into different species are geographically separated from each other (allopatric speciation) and those in which they are in close proximity (sympatric speciation). An allopatric speciation event begins with a single species that has allopatric (other land) populations, that is, populations that are geographically separated from each other and therefore in little or no contact with each other. This situation may arise when a long-distance dispersal event results in the founding of a new population that is distant from other populations of the species. An example of this would be an allopatric distribution of a species on two islands following the dispersal of one or more airborne seeds of a species from one island to the other. Allopatric distributions also arise when a widespread population system becomes fragmented into two or more allopatric systems by the formation of barriers to dispersal or by changes in climate. The rise of the Rocky Mountains and the corresponding formation of deserts and prairies in the North American interior have created unsuitable habitats for many plant species of temperate forest environments. These species, which at one time had continuous distribution ranges across the continent, became restricted to the forests of eastern and western North America. Once a species comes to have an allopatric distribution, the separate populations begin to evolve independently, and eventually they may become differentiated from each other. This differentiation may have an adaptive basis, as the populations evolve in response to different environmental conditions. Alternatively, the differentiation may be nonadaptive and simply reflect the random origins (by mutation) and genetic fixation of new characteristics that have little or no adaptive value. This is particularly likely to occur when one of the populations is very small, as is likely to be the case when a new population is founded by a long-distance dispersal event. Although the newly formed population may grow quickly, all individuals are descended from the small number of individuals that founded the new population (possibly just one individual). A population of this sort is described as having experienced a founder event, in which it goes through a "genetic bottleneck" and characteristics that were rare in the ancestral population but happened to occur among the founding individuals of the new population may occur in all individuals of the new population under these various circumstances.

As differentiation of allopatric populations proceeds, the point is eventually reached at which two species are recognized. Under the phylogenetic species criterion (criterion 1), speciation can be regarded as having been completed as soon as there are one or more genetically determined differences between the two populations, such that all individuals of one population are distinct from all individuals of the other. For example, all individuals on one island may have teeth on the margins of their leaves, while all of those on another island may lack such teeth. An intermediate stage in this process could be recognized when a particular characteristic is present in only one of the populations (possibly having arisen as a new mutation in that population), but this characteristic does not occur in all individuals of that population.

Singh, R. S. & Kulathinal, R. J. Sex gene pool evolution and speciation: a new paradigm. Genes Genet. Syst. 75, 119–130 (2000).

Vacquier, V. D. Evolution of gamete recognition proteins. Science 281, 1995–1998 (1998).

Civetta, A. & Singh, R. S. High divergence of reproductive tract proteins and their association with postzygotic reproductive isolation in Drosophila melanogaster and Drosophila virilis group species. J. Mol. Evol. 41, 1085–1095 (1995).An important paper showing that, on average, Drosophila reproductive proteins are about twice as diverse as non-reproductive proteins.

Yang, Z. & Bielawski, J. P. Statistical methods for detecting molecular adaptation. Trends Ecol. Evol. 15, 496–503 (2000). An excellent review on the use of the d N/d S ratio to detect adaptive evolution (positive Darwinian selection).

Makalowski, W. & Boguski, M. S. Evolutionary parameters of the transcribed mammalian genome: an analysis of 2,820 orthologous rodent and human sequences. Proc. Natl Acad. Sci. USA 95, 9407–9412 (1998).The authors compare many genes between rodents and humans, and provide a good database for the comparison of rapidly, and non-rapidly, evolving genes.

Li, W.-H. Molecular Evolution (Sinauer Associates, Sunderland, Massachusetts, 1997).

Lee, Y. H., Ota, T. & Vacquier, V. D. Positive selection is a general phenomenon in the evolution of abalone sperm lysin. Mol. Biol. Evol. 12, 231–238 (1995).

Hughes, A. L. & Nei, M. Pattern of nucleotide substitution at major histocompatibility complex class I loci reveals overdominant selection. Nature 335, 167–170 (1988).

Yang, Z., Nielsen, R., Goldman, N. & Pedersen, A. M. Codon-substitution models for heterogeneous selection pressure at amino acid sites. Genetics 155, 431–449 (2000).

Swanson, W. J., Yang, Z., Wolfner, M. F. & Aquadro, C. F. Positive Darwinian selection drives the evolution of several female reproductive proteins in mammals. Proc. Natl Acad. Sci. USA 98, 2509–2514 (2001).This is the first demonstration of female reproductive proteins being subject to positive Darwinian selection.

Swanson, W. J., Clark, A. G., Waldrip-Dail, H. M., Wolfner, M. F. & Aquadro, C. F. Evolutionary EST analysis identifies rapidly evolving male reproductive proteins in Drosophila. Proc. Natl Acad. Sci. USA 98, 7375–7379 (2001).

Luporini, P., Vallesi, A., Miceli, C. & Bradshaw, R. A. Chemical signaling in ciliates. J. Eukaryot. Microbiol. 42, 208–212 (1995).

Ferris, P. J., Pavlovic, C., Fabry, S. & Goodenough, U. W. Rapid evolution of sex-related genes in Chlamydomonas. Proc. Natl Acad. Sci. USA 94, 8634–8639 (1997).

Ferris, P. J., Woessner, J. P. & Goodenough, U. W. A sex recognition glycoprotein is encoded by the plus mating-type gene fus1 of Chlamydomonas reinhardtii. Mol. Biol. Cell 7, 1235–1248 (1996).

Armbrust, E. V. & Galindo, H. M. Rapid evolution of a sexual reproduction gene in centric diatoms of the genus Thalassiosira. Appl. Environ. Microbiol. 67, 3501–3513 (2001).

Brown, A. J. & Casselton, L. A. Mating in mushrooms: increasing the chances but prolonging the affair. Trends Genet. 17, 393–400 (2001).

Casselton, L. A. & Olesnicky, N. S. Molecular genetics of mating recognition in basidiomycete fungi. Microbiol. Mol. Biol. Rev. 62, 55–70 (1998).

Schopfer, C. R., Nasrallah, M. E. & Nasrallah, J. B. The male determinant of self-incompatibility in Brassica. Science 286, 1697–1700 (1999).

Schopfer, C. R. & Nasrallah, J. B. Self-incompatibility. Prospects for a novel putative peptide-signaling molecule. Plant Physiol. 124, 935–940 (2000).

Kachroo, A., Schopfer, C. R., Nasrallah, M. E. & Nasrallah, J. B. Allele-specific receptor–ligand interactions in Brassica self-incompatibility. Science 293, 1824–1826 (2001).An elegant biochemical demonstration of receptor–ligand interaction that shows the specificity of reproductive proteins.

Nasrallah, J. B. Cell–cell signaling in the self-incompatibility response. Curr. Opin. Plant Biol. 3, 368–373 (2000).

Richman, A. D. & Kohn, J. R. Evolutionary genetics of self-incompatibility in the Solanaceae. Plant Mol. Biol. 42, 169–179 (2000).

Mayfield, J. A., Fiebig, A., Johnstone, S. E. & Preuss, D. Gene families from the Arabidopsis thaliana pollen coat proteome. Science 292, 2482–2485 (2001).

Hellberg, M. E. & Vacquier, V. D. Rapid evolution of fertilization selectivity and lysin cDNA sequences in teguline gastropods. Mol. Biol. Evol. 16, 839–848 (1999).

Metz, E. C., Robles-Sikisaka, R. & Vacquier, V. D. Nonsynonymous substitution in abalone sperm fertilization genes exceeds substitution in introns and mitochondrial DNA. Proc. Natl Acad. Sci. USA 95, 10676–10681 (1998).

Yang, Z., Swanson, W. J. & Vacquier, V. D. Maximum-likelihood analysis of molecular adaptation in abalone sperm lysin reveals variable selective pressures among lineages and sites. Mol. Biol. Evol. 17, 1446–1455 (2000).

Swanson, W. J. & Vacquier, V. D. Liposome fusion induced by a M(r) 18,000 protein localized to the acrosomal region of acrosome-reacted abalone spermatozoa. Biochemistry 34, 14202–14208 (1995).

Swanson, W. J. & Vacquier, V. D. Extraordinary divergence and positive Darwinian selection in a fusagenic protein coating the acrosomal process of abalone spermatozoa. Proc. Natl Acad. Sci. USA 92, 4957–4961 (1995).

Hellberg, M. E., Moy, G. W. & Vacquier, V. D. Positive selection and propeptide repeats promote rapid interspecific divergence of a gastropod sperm protein. Mol. Biol. Evol. 17, 458–466 (2000).

Swanson, W. J. & Vacquier, V. D. Concerted evolution in an egg receptor for a rapidly evolving abalone sperm protein. Science 281, 710–712 (1998).A model of species-specific fertilization based on molecular evolutionary analysis of interacting male and female reproductive proteins in plants.

Swanson, W. J., Aquadro, C. F. & Vacquier, V. D. Polymorphism in abalone fertilization proteins is consistent with the neutral evolution of the egg's receptor for lysin (VERL) and positive Darwinian selection of sperm lysin. Mol. Biol. Evol. 18, 376–383 (2001).

Vacquier, V. D., Swanson, W. J. & Hellberg, M. E. What have we learned about sea urchin sperm bindin. Dev. Growth Differ. 37, 1–10 (1995).

Palumbi, S. R. & Metz, E. C. Strong reproductive isolation between closely related tropical sea urchins (genus Echinometra). Mol. Biol. Evol. 8, 227–239 (1991).

Metz, E. C. & Palumbi, S. R. Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein bindin. Mol. Biol. Evol. 13, 397–406 (1996).

Biermann, C. H. The molecular evolution of sperm bindin in six species of sea urchins (Echinodia: Strongylocentrotidae). Mol. Biol. Evol. 15, 1761–1771 (1998).

Wolfner, M. F. Tokens of love: functions and regulation of Drosophila male accessory gland products. Insect Biochem. Mol. Biol. 27, 179–192 (1997).A review of Drosophila accessory-gland proteins, which have been included in several evolutionary studies of reproductive proteins.

Partridge, L. & Hurst, L. D. Sex and conflict. Science 281, 2003–2008 (1998).

Xue, L. & Noll, M. Drosophila female sexual behavior induced by sterile males showing copulation complementation. Proc. Natl Acad. Sci. USA 97, 3272–3275 (2000).

Chen, P. S. et al. A male accessory gland peptide that regulates reproductive behavior of female D. melanogaster. Cell 54, 291–298 (1988).

Herndon, L. A. & Wolfner, M. F. A Drosophila seminal fluid protein, Acp26Aa, stimulates egg laying in females for 1 day after mating. Proc. Natl Acad. Sci. USA 92, 10114–10118 (1995).

Heifetz, Y., Lung, O., Frongillo, Jr E. A. & Wolfner, M. F. The Drosophila seminal fluid protein Acp26Aa stimulates release of oocytes by the ovary. Curr. Biol. 10, 99–102 (2000).

Kalb, J. M., DiBenedetto, A. J. & Wolfner, M. F. Probing the function of Drosophila melanogaster accessory glands by directed cell ablation. Proc. Natl Acad. Sci. USA 90, 8093–8097 (1993).

Bertram, M. J., Neubaum, D. M. & Wolfner, M. F. Localization of the Drosophila male accessory gland protein Acp36DE in the mated female suggests a role in sperm storage. Insect Biochem. Mol. Biol. 26, 971–980 (1996).

Neubaum, D. M. & Wolfner, M. F. Mated Drosophila melanogaster females require a seminal fluid protein, Acp36DE, to store sperm efficiently. Genetics 153, 845–857 (1999).

Tram, U. & Wolfner, M. F. Male seminal fluid proteins are essential for sperm storage in Drosophila melanogaster. Genetics 153, 837–844 (1999).

Chapman, T., Liddle, L. F., Kalb, J. M., Wolfner, M. F. & Partridge, L. Cost of mating in Drosophila melanogaster females is mediated by male accessory gland products. Nature 373, 241–244 (1995).

Harshman, L. G. & Prout, T. Sperm displacement without sperm transfer in Drosophila melanogaster. Evolution 48, 758–766 (1994).

Clark, A. G., Aguade, M., Prout, T., Harshman, L. G. & Langley, C. H. Variation in sperm displacement and its association with accessory gland protein loci in Drosophila melanogaster. Genetics 139, 189–201 (1995).

Tsaur, S. C. & Wu, C. I. Positive selection and the molecular evolution of a gene of male reproduction, Acp26Aa of Drosophila. Mol. Biol. Evol. 14, 544–549 (1997).

Tsaur, S. C., Ting, C. T. & Wu, C. I. Positive selection driving the evolution of a gene of male reproduction, Acp26Aa, of Drosophila. II. Divergence versus polymorphism. Mol. Biol. Evol. 15, 1040–1046 (1998).

Begun, D. J., Whitley, P., Todd, B. L., Waldrip-Dail, H. M. & Clark, A. G. Molecular population genetics of male accessory gland proteins in Drosophila. Genetics 156, 1879–1888 (2000).

Aguade, M. Positive selection drives the evolution of the Acp29AB accessory gland protein in Drosophila. Genetics 152, 543–551 (1999).

Fuyama, Y. Species-specificity of paragonial substances as an isolating mechanism in Drosophila. Experientia 39, 190–192 (1983).

Wyckoff, G. J., Wang, W. & Wu, C. I. Rapid evolution of male reproductive genes in the descent of man. Nature 403, 304–309 (2000).This paper shows that rapidly evolving reproductive proteins occur in organisms with complex mating courtships.

Wassarman, P. M. Mammalian fertilization: molecular aspects of gamete adhesion, exocytosis, and fusion. Cell 96, 175–183 (1999).

Yurewicz, E. C., Sacco, A. G., Gupta, S. K., Xu, N. & Gage, D. A. Hetero-oligomerization-dependent binding of pig oocyte zona pellucida glycoproteins ZPB and ZPC to boar sperm membrane vesicles. J. Biol. Chem. 273, 7488–7494 (1998).

Chen, J., Litscher, E. S. & Wassarman, P. M. Inactivation of the mouse sperm receptor, mZP3, by site-directed mutagenesis of individual serine residues located at the combining site for sperm. Proc. Natl Acad. Sci. USA 95, 6193–6197 (1998).

Eidne, K. A., Henery, C. C. & Aitken, R. J. Selection of peptides targeting the human sperm surface using random peptide phage display identify ligands homologous to ZP3. Biol. Reprod. 63, 1396–1402 (2000).

Gao, Z. & Garbers, D. L. Species diversity in the structure of zonadhesin, a sperm-specific membrane protein containing multiple cell adhesion molecule-like domains. J. Biol. Chem. 273, 3415–3421 (1998).

Juneja, R., Agulnik, S. I. & Silver, L. M. Sequence divergence within the sperm-specific polypeptide TCTE1 is correlated with species-specific differences in sperm binding to zona-intact eggs. J. Androl. 19, 183–188 (1998).

Higgie, M., Chenoweth, S. & Blows, M. W. Natural selection and the reinforcement of mate recognition. Science 290, 519–521 (2000).

Hill, K. L. & L'Hernault, S. W. Analyses of reproductive interactions that occur after heterospecific matings within the genus Caenorhabditis. Dev. Biol. 232, 105–114 (2001).

O'Rand, M. G. Sperm–egg recognition and barriers to interspecies fertilization. Gamete Res. 19, 315–328 (1988).

Swanson, W. J. & Vacquier, V. D. The abalone egg vitelline envelope receptor for sperm lysin is a giant multivalent molecule. Proc. Natl Acad. Sci. USA 94, 6724–6729 (1997).

Kresge, N., Vacquier, V. D. & Stout, C. D. Abalone lysin: the dissolving and evolving sperm protein. Bioessays 23, 95–103 (2001).

Elder, Jr J. F. & Turner, B. J. Concerted evolution of repetitive DNA sequences in eukaryotes. Q. Rev. Biol. 70, 297–320 (1995).

McAllister, B. F. & Werren, J. H. Evolution of tandemly repeated sequences: what happens at the end of an array? J. Mol. Evol. 48, 469–481 (1999).

Wu, C. I. The genic view of the process of speciation. J. Evol. Biol. 14, 851–865 (2001).

Rieseberg, L. H., Van, F. C. & Desrochers, A. M. Hybrid speciation accompanied by genomic reorganization in wild sunflowers. Nature 375, 313–316 (1995).

Knowlton, N. Molecular genetic analyses of species boundaries in the sea. Hydrobiologia 420, 73–90 (2000).

Palumbi, S. R. Marine speciation on a small planet. Trends Ecol. Evol. 7, 114–118 (1992).

Hellberg, M. E., Balch, D. P. & Roy, K. Climate-driven range expansion and morphological evolution in a marine gastropod. Science 292, 1707–1710 (2001).

Van Doorn, G. S. Ecological versus sexual selection models of sympatric speciation. Selection (in the press).

Higashi, M., Takimoto, G. & Yamamura, N. Sympatric speciation by sexual selection. Nature 402, 523–526 (1999).

Palumbi, S. R. All males are not created equal: fertility differences depend on gamete recognition polymorphisms in sea urchins. Proc. Natl Acad Sci. USA 96, 12632–12637 (1999).This paper shows the functional consequences of diversity of reproductive proteins, and that fertilization efficiency is dependent on the genotype of the reproductive protein loci.

Biermann, C. H. & Marks, J. A. Geographic divergence of gamete recognition systems in two species in the sea urchin genus Strongylocentrotus. Zygote 8, S86–S87 (2000).

Rahman, M. A. & Uehara, T. Experimental hybridisation between two tropical species of sea urchins (genus Echinometra) in Okinawa. Zygote 8, S90 (2000).

Dieckmann, U. & Doebeli, M. On the origin of species by sympatric speciation. Nature 400, 354–357 (1999).

Kondrashov, A. S. & Shpak, M. On the origin of species by means of assortative mating. Proc. R. Soc. Lond. B 265, 2273–2278 (1998).

Kondrashov, A. S. & Kondrashov, F. A. Interactions among quantitative traits in the course of sympatric speciation. Nature 400, 351–354 (1999).

Gavrilets, S. Rapid evolution of reproductive barriers driven by sexual conflict. Nature 403, 886–889 (2000).A mathematical model that shows how the rapid evolution of genes, such as in those that encode reproductive proteins, can lead to speciation.

Wu, C. I. A stochastic simulation study on speciation by sexual selection. Evolution 39, 66–82 (1985).

Clark, A. G., Begun, D. J. & Prout, T. Female × male interactions in Drosophila sperm competition. Science 283, 217–220 (1999).

Howard, D. J. Conspecific sperm and pollen precedence and speciation. A. Rev. Ecol. Syst. 30, 109–132 (1999).

Eberhard, W. G. Female Control: Sexual Selection by Cryptic Female Choice (Princeton Univ. Press, New Jersey, 1996).

Rice, W. R. & Holland, B. The enemies within: intergenomic conflict, interlocus contest evolution (ICE), and the intraspecific Red Queen. Behav. Ecol. Sociobiol. 41, 1–10 (1997).

Gould-Somero, M. & Jaffe, L. A. in Cell Fusion and Transformation(eds Beers, R. F. & Bassett, E. G.) 27–38 (Raven, New York, 1984).

Stephano, J. L. in Abalones of the World (eds Shepherd,S. A., Tegner, M. J. & Guzman del Proo, S. A.) 518–526 (Blackwell Science, Cambridge, Massachussetts,1992).

Jaffe, L. A., Sharp, A. P. & Wolf, D. P. Absence of an electrical polyspermy block in the mouse. Dev. Biol. 96, 317–323 (1983).

Gavrilets, S., Arnqvist, G. & Friberg, U. The evolution of female mate choice by sexual conflict. Proc. R. Soc. Lond. B 268, 531–539 (2001).

Barton, N. The rapid origin of reproductive isolation. Science 290, 462–463 (2000).

Eady, P. E. Postcopulatory, prezygotic reproductive isolation. J. Zool. 253, 47–52 (2001).

Blows, M. W. Evolution of the genetic covariance between male and female components of mate recognition: an experimental test. Proc. R. Soc. Lond. B 266, 2169–2174 (1999).

Rice, W. R. Sexually antagonistic male adaptation triggered by experimental arrest of female evolution. Nature 381, 232–234 (1996).A description of a laboratory experiment showing that sexual conflict might drive the rapid evolution of reproductive proteins.

Arnqvist, G., Edvardsson, M., Friberg, U. & Nilsson, T. Sexual conflict promotes speciation in insects. Proc. Natl Acad. Sci. USA 97, 10460–10464 (2000).

Metz, E. C., Gomez-Gutierrez, G. & Vacquier, V. D. Mitochondrial DNA and bindin gene sequence evolution among allopatric species of the sea urchin genus Arbacia. Mol. Biol. Evol. 15, 185–195 (1998).

Judith Bronstein

Dr. Bronstein’s large, active lab focuses on the ecology and evolution of interspecific interactions, particularly on the poorly-understood, mutually beneficial ones (mutualisms). Using a combination of field observations, experiments, and theory, they are examining how population processes, abiotic conditions, and the community context determine net effects of interactions for the fitness of each participant species. Specific conceptual areas of interest include: (i) conflicts of interest between mutualists and their consequences for the maintenance of beneficial outcomes (ii) the causes and consequences of "cheating" within mutualism (iii) context-dependent outcomes in both mutualisms and antagonisms and (iv) anthropogenic threats to mutualisms. With Matthew Mars, she is currently extending these concepts to explore educational "ecosystems" in the state of Arizona, as well as terrorist networks and how principles of ecosystem organization can be used to disrupt them.


Ecology, Species interactions, Professional skills for graduate students, biology outreach to Tucson K-12 schools.