Imitating the cost of males: A hypothesis for coexistence of all‐female sperm‐dependent species and their sexual host

Breton

Angers

2018

PeerJ

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BackgroundSurvival in temporally or spatially changing environments is a prerequisite for the perpetuation of a given species. In addition to genetic variation, the role of epigenetic processes is crucial in the persistence of organisms. For instance, mechanisms such as developmental flexibility enable the adjustment of the phenotype of a given individual to changing conditions throughout its development. However, the extent of factors other than genetic variability, like epigenetic processes, in the production of alternative phenotype and the consequences in realized ecological niches is still unclear.MethodsIn this study, we compared the extent of realized niches between asexual and sexual individuals from different environments. We used a trait-based ecology approach exploiting trophic and locomotive structures to infer the environment that each biotype actually used. More specifically, we compared the morphology of the all-female clonal and sperm-dependent fish Chrosomus eos-neogaeus to that of their sexual host species C. eos in common garden and natural conditions.ResultsTransfer from natural to controlled conditions resulted in a similar shift in measured morphology for clonal and sexual individuals suggesting comparable level of flexibility in both kinds of organisms. However, clonal, but not sexual, individuals displayed a consistent phenotype when reared in uniform conditions indicating that in absence of genetic variation, one phenotype corresponds to one niche. This contrasted with results from natural conditions where clones were morphologically as variable as sexual individuals within a sampled site. In addition, similar phenotypic changes for both clonal and sexual individuals were observed among the majority of sampled sites, indicating that they responded similarly to the same environments.DiscussionOur results indicated that clones can efficiently use different niches and may evolve in a range of environmental conditions comparable to that of a sexual species, thus underlying the importance of factors other than genetic variability, like epigenetic processes, for coping with environmental heterogeneity.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A trait-based ecology to assess the acclimation of a sperm-dependent clonal fish compared to its sexual host

Breton

Angers

2018

PeerJ

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“…In the Chrosomus eos–neogaeus complex, a high proportion of triploid hybrids are produced by the incorporation of the sperm genome into the diploid hybrids’ eggs (Goddard et al, ; Leung & Angers, ). Since triploid hybrids display both the consensus multilocus genotype of a given hybrid lineage and the spermatozoid haplome, it was possible to identify the hybrid lineage from which they derived.…”

Section: Methodsmentioning

confidence: 99%

“…This reproduction period must overlap with that of one of the parental species because the reproduction of the hybrids requires the sperm of a parental species to activate the development of their eggs (gynogenesis). In addition, the asexual reproduction of all‐female clonal hybrids is expected to result in a rapid demographic expansion of hybrid population (Leung & Angers, ). The high abundance of sperm‐dependent female hybrids compared to the low number of remaining late C. neogaeus females may prevent or strongly reduce the probability of further hybridization events.…”

Section: Introductionmentioning

confidence: 99%

Inferring responses to climate warming from latitudinal pattern of clonal hybridization

Monette

Lafond

et al. 2019

Ecology and Evolution

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Climate warming may affect reproductive isolation between sympatric sister species by modifying reproductive phenology or mate choice. This is expected to result in a latitudinal progression of hybridization in response to the shifting of environmental conditions. The fish species northern redbelly dace (Chrosomus eos) and finescale dace (C. neogaeus) display a wide sympatric distribution in North America. The asexual reproduction of their hybrids allows determining where and when hybridization occurred. The aim of this study was twofold: first, to assess whether temperature affected reproductive isolation, and second, whether the effects of climate warming resulted in a latitudinal progression of hybridization. We performed a 500 km latitudinal survey (51 sites) in southeastern Quebec (Canada) and determined the distribution of clonal hybrid lineages. Results revealed a total of 78 hybrid lineages, including 70 which originated locally. We detected a significant difference between the southern and northern range of the survey in terms of the proportion of sites harboring local hybrids (20/23 vs. 8/28 sites, respectively) and hybrid diversity (57 vs. 13 lineages, respectively). This confirmed that there was more frequent interspecific mating in the warmest sites. In the southern range, diversity of lineages and simulations suggest that hybridization first took place (>7,000 years) in sites characterized by a longer growing season, followed by northerly adjacent sites (ca. 3,500-5,000 years).Moreover, evidence of hybridization occurring in present-day time was detected.This suggests that the current warming episode is going beyond the limits of the previous warmest period of the Holocene. K E Y W O R D SChrosomus eos-neogaeus complex, clonal hybrid, global warming, hybridization, latitudinal distribution, premating barriers

“…These hybrids reproduce clonally by gynogenesis; sperm of either C. eos or C. neogaeus is required, but only to trigger the development of the unreduced eggs (Goddard, Megwinoff, Wessner, & Giaimo, ). However, a high proportion of triploid hybrids may occur when the nuclear genome of C. eos sperm is incorporated in unreduced hybrid eggs (Leung & Angers, ). Triploid hybrids are expected to occasionally produce eggs with a haploid C. eos genome and C. neogaeus mtDNA (Goddard & Schultz, ).…”

Section: Introductionmentioning

confidence: 99%

The effects of allospecific mitochondrial genome on the fitness of northern redbelly dace (Chrosomus eos)

Angers

Vétil

et al. 2018

Ecology and Evolution

Self Cite

Instantaneous mitochondrial introgression events allow the disentangling of the effects of hybridization from those of allospecific mtDNA. Such process frequently occurred in the fish Chrosomus eos, resulting in cybrid individuals composed of a C. eos nuclear genome but with a C. neogaeus mtDNA. This provides a valuable model to address the fundamental question: How well do introgressed individuals perform in their native environment? We infer where de novo production of cybrids occurred to discriminate native environments from those colonized by cybrids in 25 sites from two regions (West‐Qc and East‐Qc) in Quebec (Canada). We then compared the relative abundance of wild types and cybrids as a measure integrating both fitness and de novo production of cybrids. According to mtDNA variation, 12 introgression events are required to explain the diversity of cybrids. Five cybrid lineages could not be associated with in situ introgression events. This includes one haplotype carried by 93% of the cybrids expected to have colonized West‐Qc. These cybrids also displayed a nearly complete allopatric distribution with wild types. We still inferred de novo production of cybrids at seven sites, that accounted for 70% of the cybrids in East‐Qc. Wild‐type and cybrid individuals coexist in all East‐Qc sites while cybrids were less abundant. Allopatry of cybrids restricted to the postglacial expansion suggests the existence of higher fitness for cybrids in specific conditions, allowing for the colonization of different environments and expanding the species’ range. However, allospecific mtDNA does not provide a higher fitness to cybrids in their native environment compared to wild types, making the success of an introgressed lineage uncertain.