scholarly journals Species integrity enhanced by a predation cost to hybrids in the wild

2017 ◽  
Vol 13 (7) ◽  
pp. 20170208 ◽  
Author(s):  
P. Anders Nilsson ◽  
Kaj Hulthén ◽  
Ben B. Chapman ◽  
Lars-Anders Hansson ◽  
Jakob Brodersen ◽  
...  
Keyword(s):  
Related Species ◽  
Parental Species ◽  
Great Cormorant ◽  
Phalacrocorax Carbo ◽  
Hybrid Fitness ◽  
Closely Related Species ◽  
Ecological Selection ◽  
Field Evidence ◽  
In The Wild ◽  
Species Integrity

Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of parental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post-zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of-concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama ) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo ). Scanning for regurgitated tags under cormorant roosts 3–4 years later identified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.

scholarly journals Living a dog’s life: a putative gray wolf in a feral dog group

Mammalia ◽  
2020 ◽  
Vol 84 (2) ◽  
pp. 115-120
Author(s):  
Elitsa Popova ◽  
Diana Zlatanova
Keyword(s):  
Related Species ◽  
Ecological Impact ◽  
Complex Interaction ◽  
Domestic Dog ◽  
Hybrid Origin ◽  
Mountainous Area ◽  
Gray Wolf ◽  
Closely Related Species ◽  
Feral Dogs ◽  
In The Wild

AbstractThe gray wolf and the domestic dog are closely related species that can interbreed and produce fertile offspring. In settings where unrestrained dogs are present in the wild, hybridization can happen naturally. However, the behavior of the resulting hybrids and their ecological impact is largely understudied. In September–November 2018, a putative gray wolf was repeatedly camera-trapped in a group of 10 presumably feral dogs in a remote mountainous area (the Osogovo Mountain) along the border between Bulgaria and North Macedonia. The most feasible explanation for this individual’s atypical behavior is that it is of hybrid origin (assumption based on phenotype). To the best of our knowledge, this is the first documented observation of such a kind. A discussion of its recruitment and position in the group is presented, setting the basis for further investigation of the complex interaction between wolves, dogs and hybrids in the wild.

Reproductive isolation between two closely related species of the Queensland fruit fly Dracus tryoni (Frogg) and D. neohumeralis Hardy (Diptera : Tephritidae) I. Variation in humeral callus pattern and the occurrence of intermediate colour forms in the wild

1967 ◽  
Vol 15 (3) ◽  
pp. 501 ◽  
Author(s):  
H Wolda
Keyword(s):  
Reproductive Isolation ◽  
Related Species ◽  
Fruit Fly ◽  
Abundant Species ◽  
Colour Pattern ◽  
Wild Populations ◽  
Closely Related Species ◽  
Similar Variation ◽  
In The Wild

A number of samples from wild populations of the Queensland fruit fly, Dacus tryoni and D. neohumeralis, were studied. There is a considerable variation in the colour pattern on the humeral callus. This variation is continuous so that any criterion for distinguishing between "intermediates" and "good species" is purely arbitrary. It was found in areas where D. neohumeralis does not occur as well as in localities where it is very abundant. By whatever criterion one defines intermediates, there appears to be no relation between the frequency of such forms and the presence or absence of D. neohumeralis or with the relative proportions of the two species in the population. However, flies with only a very small yellow area on an otherwise brown humeral callus were found only in Cairns where D. neohumeralis is usually the most abundant species. A similar variation in humeral callus pattern was found in other related species, such as D. kraussi and D. halfordiae. It is concluded that the intermediate colour forms may not be hybrids between D. tryoni and D. neohumeralis but variants of D. tryoni and, possibly the darker forms from Cairns, of D. neohumeralis.

scholarly journals Limited intrinsic postzygotic reproductive isolation despite chromosomal rearrangements between closely related sympatric species of small ermine moths (Lepidoptera: Yponomeutidae)

2019 ◽  
Vol 128 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Katerina H Hora ◽  
František Marec ◽  
Peter Roessingh ◽  
Steph B J Menken
Keyword(s):  
Reproductive Isolation ◽  
Parental Species ◽  
Meiotic Chromosome ◽  
Chromosomal Rearrangements ◽  
Sympatric Species ◽  
Hybrid Fitness ◽  
New Host ◽  
Closely Related Species ◽  
Postzygotic Reproductive Isolation

Abstract In evolutionarily young species and sympatric host races of phytophagous insects, postzygotic incompatibility is often not yet fully developed, but reduced fitness of hybrids is thought to facilitate further divergence. However, empirical evidence supporting this hypothesis is limited. To assess the role of reduced hybrid fitness, we studied meiosis and fertility in hybrids of two closely related small ermine moths, Yponomeuta padella and Yponomeuta cagnagella, and determined the extent of intrinsic postzygotic reproductive isolation. We found extensive rearrangements between the karyotypes of the two species and irregularities in meiotic chromosome pairing in their hybrids. The fertility of reciprocal F1 and, surprisingly, also of backcrosses with both parental species was not significantly decreased compared with intraspecific offspring. The results indicate that intrinsic postzygotic reproductive isolation between these closely related species is limited. We conclude that the observed chromosomal rearrangements are probably not the result of an accumulation of postzygotic incompatibilities preventing hybridization. Alternative explanations, such as adaptation to new host plants, are discussed.

scholarly journals A pre-zygotic barrier to hybridization in two con-generic species of scleractinian corals

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 193 ◽  
Author(s):  
Andrew H. Baird ◽  
Vivian R. Cumbo ◽  
Joana Figueiredo ◽  
Saki Harii
Keyword(s):  
Related Species ◽  
Scleractinian Corals ◽  
Evolutionary Novelty ◽  
Closely Related Species ◽  
Potential Source ◽  
The Family ◽  
Growing Body ◽  
In The Wild

Hybridization is often cited as a potential source of evolutionary novelty in the order Scleractinia. While hybrid embryos can be produced in vitro, it has been difficult to identify adult hybrids in the wild. Here, we tested the potential for hybridization between two closely related species in the family Fungiidae. We mixed approximately 5000 eggs of Ctenactis echinata with sperm from Ctenactis crass. No hybrid embryos were produced. This observation adds to a growing body of evidence for pre-zygotic barriers to hybridization in corals and challenges the claim that hybridization is a major source of evolutionary novelty in the order.

scholarly journals The relationship between gene flow and population difference during secondary contact between butterfly sister species

2020 ◽  
Author(s):  
Erik D. Nelson ◽  
Qian Cong ◽  
Nick V. Grishin
Keyword(s):  
Gene Flow ◽  
Related Species ◽  
Missing Values ◽  
Sudden Change ◽  
Secondary Contact ◽  
Z Chromosome ◽  
Population Difference ◽  
Hybrid Fitness ◽  
Closely Related Species ◽  
Index Data

AbstractClosely related species of butterfly sampled from southern suture zones in North America exhibit a continuous pattern of gene flow and population difference measures (index values) for autosomes, but not for the Z chromosome; When populations are compared through their Z chromosomes, index values obtained from samples of the same species are separated from those of closely related species by a gap of “missing” values, suggesting a discrete “on–off” criterion for species delimitation. Here, we explore the possibility that some, or all of the index data for suture zones reflects secondary contact between species formed in glacial refugia. We simulate fusion of butterfly populations limited by negative fitness interactions between genes in hybrids, assuming that interactions between autosomes and the Z chromosome are stronger than those among autosomes, and that hybrid fitness effects conform to Haldane’s rule. We find that weakly interbreeding populations trace out a path toward equilibrium consistent with the data for butterfly suture zones, in which index values for the Z chromosome lag behind those for autosomes, leading to a similar gap of missing values when species become indistinguishable through their autosomes, but no evidence of a sudden change in index values for the Z chromosome on longer timescales. As a result, we find that the gap can be explained by a process in which the pattern of index data for the Z chromosome is, ultimately, continuous.

Hybridisation Between Black (Pteropods alecto) and Grey- Headed (P. poliocephalus) Flying-Foxes (Megachiroptera: Pteropodidae).

1995 ◽  
Vol 18 (1) ◽  
pp. 19
Author(s):  
N.J. Webb ◽  
C.R. Tidemann
Keyword(s):  
Parental Species ◽  
Interspecific Hybridisation ◽  
Morphological Similarity ◽  
Closely Related Species ◽  
Flying Foxes ◽  
Heterozygous Condition ◽  
Allelic Differences ◽  
In The Wild ◽  
External Characteristics ◽  
Flying Fox

The range of the black flying-fox (Pteropus alecto) in Australia overlaps with two morphologically very similar congenerics: the grey-headed flying-fox (P. poliocephalus) and the spectacled flying-fox (P. conspecillatus). Protein electrophoresis was used to examine cases of apparent hybridisation between P. alecto and these other species. Two loci with fixed allelic differences were identified between P. alecto and P. poliocephalus and were used to confirm three cases of interspecific hybridisation, one of which probably occurred in the wild, and one of backcrossing. Hybrid individuals possessed external characteristics that were intermediate between the parental species. Pteropus alecto and P. conspecillatus showed very little genetic differentiation and only one out of 23 scorable loci showed a fixed allelic difference. A reported interspecific hybrid, and two other flying-foxes, considered to be possible P. alecto/P. conspecillatus hybrids, failed to show the expected heterozygous condition at this locus. Further diagnostic loci need to be sought before a definite conclusion can be made concerning the hybrid status of these individuals. The very close morphological similarity of P. alecto and P. conspecillatus, combined with their genetic similarity, suggests that more discriminating DNA based techniques would be necessary to fully describe the relationships between these closely related species.

scholarly journals Rearing animals in captivity for the study of trematode life histories. II

1940 ◽  
Vol 24 (2) ◽  
pp. 613-617 ◽  
Author(s):  
Miriam Rothschild
Keyword(s):  
Related Species ◽  
Life Histories ◽  
Adult Fluke ◽  
Morphological Comparison ◽  
Closely Related Species ◽  
In Captivity ◽  
Previous Infection ◽  
In The Wild

The advantage of using laboratory-reared animals in the elucidation of trematode life histories is now generally recognized (Palombi, 1938; Stunkard, 1938, etc.). Further researches seem to emphasize this point. No matter how carefully controls are examined and no matter how precise is the morphological comparison between cercaria, metacercaria and adult fluke, the fact that the intermediate and final hosts have been exposed to previous infection in the wild—particularly by closely related species of worms—immediately detracts from the value of the experiments.

scholarly journals A fruit in the hand or two in the bush? Divergent risk preferences in chimpanzees and bonobos

2008 ◽  
Vol 4 (3) ◽  
pp. 246-249 ◽  
Author(s):  
Sarah R Heilbronner ◽  
Alexandra G Rosati ◽  
Jeffrey R Stevens ◽  
Brian Hare ◽  
Marc D Hauser
Keyword(s):  
Decision Making ◽  
Related Species ◽  
Pan Paniscus ◽  
Risk Preferences ◽  
Food Sources ◽  
Closely Related Species ◽  
Economic Choice ◽  
Economic Decision Making ◽  
Risk Sensitive ◽  
In The Wild

Human and non-human animals tend to avoid risky prospects. If such patterns of economic choice are adaptive, risk preferences should reflect the typical decision-making environments faced by organisms. However, this approach has not been widely used to examine the risk sensitivity in closely related species with different ecologies. Here, we experimentally examined risk-sensitive behaviour in chimpanzees ( Pan troglodytes ) and bonobos ( Pan paniscus ), closely related species whose distinct ecologies are thought to be the major selective force shaping their unique behavioural repertoires. Because chimpanzees exploit riskier food sources in the wild, we predicted that they would exhibit greater tolerance for risk in choices about food. Results confirmed this prediction: chimpanzees significantly preferred the risky option, whereas bonobos preferred the fixed option. These results provide a relatively rare example of risk-prone behaviour in the context of gains and show how ecological pressures can sculpt economic decision making.

scholarly journals Hybridization and the coexistence of species

2021 ◽  
Author(s):  
Darren Irwin ◽  
Dolph Schluter
Keyword(s):  
Assortative Mating ◽  
Carrying Capacity ◽  
Related Species ◽  
Sympatric Species ◽  
Population Declines ◽  
Hybrid Fitness ◽  
Closely Related Species ◽  
Probability Of Extinction ◽  
Reproductive Rates ◽  
Incomplete Reproductive Isolation

It is thought that two species can coexist if they use different resources present in the environment, yet this assumes that species are completely reproductively isolated. Closely related species often interbreed, raising the question of how this might affect coexistence. We model coexistence outcomes for two sympatric species that are ecologically differentiated but have incomplete reproductive isolation. Results show that the consequences of interbreeding depend crucially on hybrid fitness. When hybrid fitness is high, just a small rate of hybridization can lead to collapse of two species into one. Low hybrid fitness can cause population declines, making extinction of one or both species likely. The intrinsic growth rate of the population has an important influence on the outcome. High intrinsic growth rates result in higher reproductive rates when populations are below carrying capacity, reducing the probability of extinction and increasing the likelihood of stable coexistence at moderate levels of assortative mating and hybrid fitness. Very strong but incomplete assortative mating can induce low hybrid fitness via a mating disadvantage to rare genotypes, and this can stabilize coexistence of two species at high but incomplete levels of assortative mating. Given these results and evidence that it may take many millions of years of divergence before related species become sympatric, we postulate that coexistence of closely-related species is more often limited by insufficient assortative mating than by insufficient ecological differentiation.

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