Population differentiation without speciation

Population differentiation is often viewed as an important step towards speciation, and part of the rationale for conserving variation at the intraspecific level is that the potential to generate more biological diversity should be retained. Yet, speciation is not an inevitable consequence of population divergence. This paper reviews recent work on the Trinidadian guppy, Poecilia reticulata , a species that is renowned for its capacity for population differentiation. Guppy populations evolve rapidly, within 10 to 10 2 generations, as a response to changes in selection exerted by predators. The rates of evolution involved can be up to seven orders of magnitude greater than those seen in the fossil record. Sexual selection, particuarly female choice, appears to reinforce the divergence that natural selection has generated. Perplexingly, however, there is no reproductive isolation (either prezygotic or postzygotic) between populations, even those that have been separated for at least 10 6 generations. Sexual conflict may be the key to explaining this absence of speciation. Male reproductive behaviour, particularly the high incidence of sneaky mating, may be instrumental in producing sufficient gene flow to prevent reproductive isolation. Sneaky mating has the potential to undermine female choice, and is known to be an important means of sperm transfer in wild populations. Sexual dimorphism, also a result of sexual conflict in guppies, may inhibit speciation in another way. Morphological differences between the sexes, that have arisen for reproductive reasons, mean that males and females are pre–adapted for different foraging niches. This, in turn, reduces the opportunity for the development of feeding polymorphisms, a mechanism that seems to have been important in the sympatric speciation of other fish species.

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Quantifying the gender load: can population crosses reveal interlocus sexual conflict?

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2005.1786 ◽

2006 ◽

Vol 361 (1466) ◽

pp. 363-374 ◽

Cited By ~ 32

Author(s):

Tristan A.F Long ◽

Robert Montgomerie ◽

Adam K Chippindale

Keyword(s):

Sperm Competition ◽

Sexual Conflict ◽

Population Differentiation ◽

Population Divergence ◽

Mating Frequency ◽

Female Reproduction ◽

Female Fitness ◽

Antagonistic Coevolution ◽

The Cost ◽

Sexually Antagonistic Coevolution

Six sister populations of Drosophila melanogaster kept under identical environmental conditions for greater than 600 generations were reciprocally crossed to investigate the incidence of population divergence in allopatry. Population crosses directly influenced fitness, mating frequency, and sperm competition patterns. Changes in both female remating rate and the outcome of male sperm competition (P 1 , P 2 ) in response to foreign males were consistent with intersexual coevolution. Moreover, seven of the 30 crosses between foreign mates resulted in significant reductions in female fitness, whereas two resulted in significant increases, compared to local matings. This tendency for foreign males to reduce female fitness may be interpreted as evidence for either sexually antagonistic coevolution or the disruption of mutualistic interactions. However, instances in which female fitness improved via cohabitation with foreign males may better reveal sexual conflict, signalling release from the cost of interacting with locally adapted males. By this metric, female reproduction in D. melanogaster is strongly constrained by local adaptation by males, a situation that would promote antagonistic coevolution between the sexes. We conclude that sexual selection can promote population differentiation in allopatry and that sexual conflict is likely to have played a role in population differentiation in this study system.

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Sexual selection affects the evolution of contact pheromones in Drosophila melanogaster populations isolated by differential sexual conflict

10.21203/rs.2.13749/v1 ◽

2019 ◽

Author(s):

Rochishnu Dutta ◽

Tejinder Singh Chechi ◽

N. G. Prasad

Keyword(s):

Drosophila Melanogaster ◽

Sexual Selection ◽

Reproductive Isolation ◽

Sexual Conflict ◽

Population Differentiation ◽

Lipid Profiles ◽

Mate Preference ◽

Cuticular Lipid ◽

Antagonistic Coevolution ◽

Sexually Antagonistic Coevolution

Abstract Background: The ability of sexual conflict to facilitate reproductive isolation is widely anticipated. However, very few experimental evolutionary studies have convincingly demonstrated the evolution of reproductive isolation due to sexual conflict. Recently a study on the replicates of Drosophila melanogaster populations under differential sexual conflict found that divergent mate preference evolved among replicates under high sexual conflict regime. The precopulatory isolating mechanism underlying such divergent mate preference could be sexual signals such as cuticular lipids since they evolve rapidly and are involved in D. melanogaster mate recognition. Using Drosophila melanogaster replicates used in the previous study, we investigate whether cuticular lipid divergence bears signatures of sexually antagonistic coevolution that led to reproductive isolation among replicates of high sexual conflict regime. Results: We found that their cuticular lipid profiles are sexually dimorphic. Although replicates with male biased sex ratio evolved isolation in reproductive traits due to high sexual conflict, the patterns of cuticular lipid divergence in high and low sexual conflict regimes suggest that sexual selection is the dominant selection pressure rather than sexual conflict affecting the cuticular lipid profile. We also find cuticular lipid divergence patterns to be suggestive of the Buridan’s Ass regime which is one of the six possible mechanism to resolve sexual conflict. Conclusions: Although reproductive isolation due to sexual conflict is anticipated, evolution of a sexually selected trait under sexual conflict may not lead to population differentiation in expected lines. This is because speciation due to sexually antagonistic coevolution is only one of the several outcomes of sexual conflict. This study indicates that population differentiation as a result of cuticular lipid divergence cannot be credited to sexual conflict despite high sexual conflict regime evolving divergent cuticular lipid profiles.

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Reproductive behavior

10.1093/oso/9780198797500.003.0013 ◽

2018 ◽

Cited By ~ 1

Author(s):

Rachel Olzer ◽

Rebecca L. Ehrlich ◽

Justa L. Heinen-Kay ◽

Jessie Tanner ◽

Marlene Zuk

Keyword(s):

Sexual Selection ◽

Sexual Conflict ◽

Female Choice ◽

Reproductive Behavior ◽

Mating Systems ◽

Insect Behavior ◽

Sequential Approach ◽

Evolutionary Mechanisms ◽

Anatomy And Physiology ◽

Males And Females

Sex and reproduction lie at the heart of studies of insect behavior. We begin by providing a brief overview of insect anatomy and physiology, followed by an introduction to the overarching themes of parental investment, sexual selection, and mating systems. We then take a sequential approach to illustrate the diversity of phenomena and concepts behind insect reproductive behavior from pre-copulatory mate signalling through copulatory sperm transfer, mating positions, and sexual conflict, to post-copulatory sperm competition, and cryptic female choice. We provide an overview of the evolutionary mechanisms driving reproductive behavior. These events are linked by the economic defendability of mates or resources, and how these are allocated in each sex. Under the framework of economic defendability, the reader can better understand how sexual antagonistic behaviors arise as the result of competing optimal fitness strategies between males and females.

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Quantitative Trait Loci Affecting Differences in Floral Morphology Between Two Species of Monkeyflower (Mimulus)

Genetics ◽

10.1093/genetics/149.1.367 ◽

1998 ◽

Vol 149 (1) ◽

pp. 367-382 ◽

Cited By ~ 11

Author(s):

H D Bradshaw ◽

Kevin G Otto ◽

Barbara E Frewen ◽

John K McKay ◽

Douglas W Schemske

Keyword(s):

Quantitative Trait Loci ◽

Reproductive Isolation ◽

Quantitative Trait ◽

Floral Morphology ◽

Cumulative Effect ◽

Sympatric Species ◽

Accurate Estimate ◽

Phenotypic Variance ◽

Trait Loci ◽

Morphological Differences

Abstract Conspicuous differences in floral morphology are partly responsible for reproductive isolation between two sympatric species of monkeyflower because of their effect on visitation of the flowers by different pollinators. Mimulus lewisii flowers are visited primarily by bumblebees, whereas M. cardinalis flowers are visited mostly by hummingbirds. The genetic control of 12 morphological differences between the flowers of M. lewisii and M. cardinalis was explored in a large linkage mapping population of F2 plants (n = 465) to provide an accurate estimate of the number and magnitude of effect of quantitative trait loci (QTLs) governing each character. Between one and six QTLs were identified for each trait. Most (9/12) traits appear to be controlled in part by at least one major QTL explaining ≥25% of the total phenotypic variance. This implies that either single genes of individually large effect or linked clusters of genes with a large cumulative effect can play a role in the evolution of reproductive isolation and speciation.

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Intraspecific ecomorphological variations in Poecilia reticulata (Actinopterygii, Cyprinodontiformes): comparing populations of distinct environments

Iheringia Série Zoologia ◽

10.1590/1678-476620151052217222 ◽

2015 ◽

Vol 105 (2) ◽

pp. 217-222 ◽

Cited By ~ 1

Author(s):

Fábio T. Mise ◽

Fagner de Souza ◽

João P. A. Pagotto ◽

Erivelto Goulart

Keyword(s):

Poecilia Reticulata ◽

Principal Component ◽

Water Current ◽

Way Of Life ◽

Morphological Variations ◽

Current Availability ◽

Environment Type ◽

Morphological Variables ◽

Males And Females ◽

Morphological Differences

ABSTRACT Morphological variations, according to the principles of ecomorphology, can be related to different aspects of the organism way of life, such as occupation of habitats and feeding behavior. The present study sought to examine the intraspecific variation in two populations of Poecilia reticulata Peters, 1859, that occur in two types of environments, a lotic (Maringá Stream) and a lentic (Jaboti Lake). Due to a marked sexual dimorphism, males and females were analyzed separately. Thus, the proposed hypotheses were that the populations that occur in distinct environments present morphological differences. The morphological variables were obtained using morphometric measurements and the ecomorphological indexes. The data were summarized in a Principal Component Analysis (PCA). A Multivariate Analysis of Variance (Manova) was made to verify significant differences in morphology between the populations. Males and females showed similar ecomorphological patterns according to the environment they occur. In general the population from Maringá Stream had fins with major areas, and the Jaboti Lake population eyes located more dorsally. Additionally, others morphological differences such as wider mouth of the males from Maringá Stream, wider heads on Jaboti Lake females and more protractible mouths on males from Jaboti Lake suggest a set of environmental variables that can possibly influence the ecomorphological patterns of the populations, as the water current, availability of food resources and predation. In summary, the initial hypotheses could be confirmed, evidencing the occurrence of distinct ecomorphotypes in the same species according to the environment type.

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Offspring quality and female choice in the guppy,Poecilia reticulata

Animal Behaviour ◽

10.1006/anbe.1995.0050 ◽

1995 ◽

Vol 49 (2) ◽

pp. 377-387 ◽

Cited By ~ 48

Author(s):

PAUL F. NICOLETTO

Keyword(s):

Female Choice ◽

Poecilia Reticulata ◽

Offspring Quality

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Phenotypic Dimensions of Reproductive Isolation Between Northern and Melissa Blue Butterflies in the Rocky Mountains

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.2011.3795 ◽

2011 ◽

Vol 33 ◽

pp. 101-105

Author(s):

Zachariah Gompert

Keyword(s):

Reproductive Isolation ◽

Biological Diversity ◽

Butterfly Species ◽

General Importance ◽

Greater Yellowstone Area ◽

Single Character ◽

Character Variation ◽

Greater Yellowstone ◽

Species Speciation

Biological diversity results from speciation, which generally involves the splitting of an ancestral species into descendant species due to adaptation to different niches or the evolution of reproductive incompatibilities (Coyne and Orr 2004). The diverse flora and fauna of the world, including the native inhabitants of the Greater Yellowstone Area (GYA), exist as a result of the speciation process. The central role speciation plays in generating biological diversity imbues importance to our understanding of this process. The general importance of a thorough understanding of speciation is amplified because of the current high rates of extinction on the planet. This is because a long term solution to the present extinction crisis will require maintaining the processes that create species (speciation) not simply preventing extinction. However, many central questions regarding speciation remain to be answered. One fundamental question in speciation research is whether diverging species are isolated (i.e., prevented from interbreeding) due to differences in one, a few, or many characters and whether each of these character differences results from different alleles at a few or many genes. For example, speciation and reproductive isolation might involve divergence along multiple phenotypic axes, such as mate preference, habitat use or preference, and phenology (the timing of life-cycle events). Alternatively, isolation could result from differentiation of a single character. I propose to address this question by assessing patterns of variation for a suite of characters across a hybrid zone between two butterfly species. This is possible because patterns of character variation across hybrids zones allow for inferences about reproductive isolation (Barton and Hewitt 1985).

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