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opencc-zeroAug 2020View details →

More than meets the eye: syntopic and morphologically similar mangrove killifish species show different mating systems and patterns of genetic structure along the Brazilian coast

<a name="_Hlk40344892">Different mating systems can strongly affect the extent of genetic diversity and population structure among species. Given the increased effects of genetic drift on reduced population size, theory predicts that species undergoing self-fertilization should have greater population structure than outcrossed species, however demographic dynamics may affect this scenario. </a>The mangrove killifish clade is composed of the two only known examples of self-fertilising species among vertebrates (Kryptolebias marmoratus and K. hermaphroditus). A third species in this clade, K. ocellatus, inhabits mangrove forests in southeast Brazil, however its mating system and patterns of genetic structure have been rarely explored. Here, we examined the genetic structure and phylogeographic patterns of K. ocellatus along its distribution, using mitochondrial DNA and microsatellites to compare its patterns of genetic structure with the predominantly selfing and often syntopic, K. hermaphroditus. Our results indicate that K. ocellatus reproduces mainly by outcrossing across much of its known range, with no current evidence of selfing, despite being an androdioecious species. Our results also reveal a stronger population subdivision in K. ocellatus compared to K. hermaphroditus, contrary to the theoretical predictions based on reproductive biology of the two species. Our findings indicate that, although morphologically similar, K. ocellatus and K. hermaphroditus had remarkably different evolutionary histories when colonising the same mangrove areas in south-eastern Brazil, with other factors (e. g. time of colonisation, dispersal/establishment capacity) having more profound effects on the current population structuring of those species than differences in mating systems.

opencc-zeroDec 2020View details →

Supplementary material 1 from: Guedes GHS, Salgado FLK, Uehara W, de Pavia Ferreira DL, Araújo FG (2020) The recapture of Leptopanchax opalescens (Aplocheiloidei: Rivulidae), a critically endangered seasonal killifish: habitat and aspects of population structure. Zoologia 37: 1-8. https://doi.org/10.3897/zoologia.37.e54982

Figure S1. Photographic records of Leptopanchax opalescens in an aquarium after three hours of capture (Photos 1–3), and record of a male specimen with more exuberant color immediately after capture in its natural habitat (Photos 4–5). Date: March 19th, 2020; Coordinates: 22°42.35'S, 43°41.59'W.

FIGURE 6 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 6. Type locality of Nothobranchius elucens; Uganda: upper Nile drainage: ephemeral swamp in the Aringa system. Photographed on 6 June 2017.

FIGURE 4 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 4. Nothobranchius elucens, female, about 25 mm SL, live; Uganda: upper Nile drainage: ephemeral swamp in the Aringa system, about 2.6 km south of Madi Opei town. Photographed after two weeks in captivity.

FIGURE 7. Nothobranchius taiti, MRAC 2018.015.P.0002 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 7. Nothobranchius taiti, MRAC 2018.015.P.0002, paratype, male, 35.3 mm SL, live; Uganda: upper Nile drainage: Lake Kyoga basin: ephemeral swamp of the Apapi River system. Photographed after 2 weeks in captivity.

FIGURE 1 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 1. Comparative morphometry in males of Nothobranchius elucens (blue triangles) and N. taiti (green squares). Score plot of principal component analysis on the best subset of morphometric characters; first vs. second principal components.

FIGURE 2. Nothobranchius elucens, MRAC 2020.007.P.0001 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 2. Nothobranchius elucens, MRAC 2020.007.P.0001, holotype, male, 31.9 mm SL; Uganda: upper Nile drainage: ephemeral swamp in the Aringa system, about 2.6 km south of Madi Opei town.

FIGURE 3. Nothobranchius elucens, MRAC 2020.007.P.0008 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 3. Nothobranchius elucens, MRAC 2020.007.P.0008, paratype, male, 35.7 mm SL, live; Uganda: upper Nile drainage: ephemeral swamp in the Aringa system, about 2.6 km south of Madi Opei town. Photographed after one month in captivity.

FIGURE 5 in Nothobranchius elucens, a new species of seasonal killifish from the upper Nile drainage in Uganda (Cyprinodontiformes: Nothobranchiidae)

FIGURE 5. Map of Uganda, showing the type locality of Nothobranchius elucens (blue triangle) and N. taiti (green squares). Map prepared by Brian Watters.

opencc-zeroDec 2016View details →

Data from: Plio-Pleistocene phylogeography of the Southeast Asian Blue Panchax killifish, Aplocheilus panchax

The complex climatic and geological history of Southeast Asia has shaped this region's high biodiversity. In particular, sea level fluctuations associated with repeated glacial cycles during the Pleistocene both facilitated, and limited, connectivity between populations. In this study, we used data from two mitochondrial and three anonymous nuclear markers to determine whether a fresh/brackish water killifish, Aplocheilus panchax, Hamilton, 1822, could be used to further understand how climatic oscillations and associated sea level fluctuations have shaped the distribution of biota within this region, and whether such patterns show evidence of isolation within palaeodrainage basins. Our analyses revealed three major mitochondrial clades within A. panchax. The basal divergence of A. panchax mitochondrial lineages was approximately 3.5 Ma, whilst the subsequent divergence timings of these clades occurred early Pleistocene (~2.6 Ma), proceeding through the Pleistocene. Continuous phylogeographic analysis showed a clear west-east dispersal followed by rapid radiation across Southeast Asia. Individuals from Krabi, just north of the Isthmus of Kra, were more closely related to the Indian lineages, providing further evidence for a freshwater faunal disjunction at the Isthmus of Kra biogeographic barrier. Our results suggest that Sulawesi, across the Wallace Line, was colonised relatively recently (~30 ka). Nuclear DNA is less geographically structured, although Mantel tests indicated that nuclear genetic distances were correlated with geographic proximity. Overall, these results imply that recent gene flow, as opposed to historical isolation, has been the key factor determining patterns of nuclear genetic variation in A. panchax, however, some evidence of historical isolation is retained within the mitochondrial genome. Our study further validates the existence of a major biogeographic boundary at the Kra Isthmus, and also demonstrates the use of widely distributed fresh/brackishwater species in phylogeographic studies, and their ability to disperse across major marine barriers in relatively recent time periods.

opencc-zeroDec 2013View details →

Data from: The meaning of melanin, carotenoid, and pterin pigments in the bluefin killifish, Lucania goodei

Male bluefin killifish (Lucania goodei) exhibit extensive color variation in their fins, but the utility of this variation has not yet been determined. We collected males from multiple populations and spectrophotometrically determined the pigment types responsible for fin coloration. We determined that the orange coloration in the caudal fin is caused by carotenoid pigmentation. In contrast, color in the anal fin is either pterin based (yellow and red) or structural (blue) with a melanic fin border. As these colors have different developmental origins, the potential for complex signaling is high. Therefore, we sought to determine whether behavior, reproductive success, or health correlated with pigmentation. Males with more melanin on the anal fin were more dominant and had higher spawning success. Male–male aggression was greater between males with similar-sized melanic borders, indicating that melanic markings function as badges of status between males. Caudal carotenoid pigmentation did not correlate with dominance, but this highly labile ornament was correlated with body condition, parasite infection, and spawning success, suggesting a role in intersexual selection by signaling health to potential mates. Similar results were found for caudal fin coloration using digital photography. Pterin pigmentation in the anal fin was not related to dominance but was related to overall spawning levels and parasite infection, suggesting that pterin pigmentation may also signal immune status. Thus, the coloration of male bluefin killifish provides multiple messages to multiple receivers through these 3 pigments (melanin, pterin, and carotenoid) that have distinct developmental origins.

opencc-zeroDec 2013View details →

Data from: Genetic diversity and population history of the endangered killifish Aphanius baeticus

The secondary freshwater fish fauna of the western-Iberian Peninsula basin is primarily restricted to local coastal streams, and man-made salt evaporation ponds, etc., which are susceptible to periodical flood and drought events. Despite its uniqueness in ecological adaptation to high saltwater tolerance, very little is known about this fauna's population dynamics and evolutionary history. The killifish, Aphanius baeticus (Cyprinodontidae) is an endemic species restricted to river basins on Spain's southern Atlantic coastline, considered as "Endangered." In this study, the genetic structure, diversity and historical demography of A. baeticus were analyzed using mitochondrial (cytochrome b, N = 131) and nuclear (4 out of 19 microsatellites tested, N = 288) markers across its distribution range. The phylogenetic and networking reconstruction revealed subtle phylogeographic structuring. A scattered expansion at the beginning of the interglacial periods, coupled with posterior events of extinction and colonization caused by periodical cycles of flooding, could explain the absence of well-defined phylogenetic relationships among populations. Moreover, very low genetic diversity values and a weak population differentiation were detected. We proposed that dispersals allowed by periodic floods connecting river drainages may have promoted a wide genetic exchange among populations and could have contributed to the current genetic relatedness of these populations.

opencc-zeroDec 2013View details →

Data from: Genetic variation at aryl hydrocarbon receptor (AHR) loci in populations of Atlantic killifish (Fundulus heteroclitus) inhabiting polluted and reference habitats

Background: The non-migratory killifish Fundulus heteroclitus inhabits clean and polluted environments interspersed throughout its range along the Atlantic coast of North America. Several populations of this species have successfully adapted to environments contaminated with toxic aromatic hydrocarbon pollutants such as polychlorinated biphenyls (PCBs). Previous studies suggest that the mechanism of resistance to these and other "dioxin-like compounds" (DLCs) may involve reduced signaling through the aryl hydrocarbon receptor (AHR) pathway. Here we investigated gene diversity and evidence for positive selection at three AHR-related loci (AHR1, AHR2, AHRR) in F. heteroclitus by comparing alleles from seven locations ranging over 600 km along the northeastern US, including extremely polluted and reference estuaries, with a focus on New Bedford Harbor (MA, USA), a PCB Superfund site, and nearby reference sites. Results: We identified 98 single nucleotide polymorphisms within three AHR-related loci among all populations, including synonymous and nonsynonymous substitutions. Haplotype distributions were spatially segregated and F-statistics suggested strong population genetic structure at these loci, consistent with previous studies showing strong population genetic structure at other F. heteroclitus loci. Genetic diversity at these three loci was not significantly different in contaminated sites as compared to reference sites. However, for AHR2 the New Bedford Harbor population had significant FST values in comparison to the nearest reference populations. Tests for positive selection revealed ten nonsynonymous polymorphisms in AHR1 and four in AHR2. Four nonsynonymous SNPs in AHR1 and three in AHR2 showed large differences in base frequency between New Bedford Harbor and its reference site. Tests for isolation-by-distance revealed evidence for non-neutral change at the AHR2 locus. Conclusion: Together, these data suggest that F. heteroclitus populations in reference and polluted sites have similar genetic diversity, providing no evidence for strong genetic bottlenecks for populations in polluted locations. However, the data provide evidence for genetic differentiation among sites, selection at specific nucleotides in AHR1 and AHR2, and specific AHR2 SNPs and haplotypes that are associated with the PCB-resistant phenotype in the New Bedford Harbor population. The results suggest that AHRs, and especially AHR2, may be important, recurring targets for selection in local adaptation to dioxin-like aromatic hydrocarbon contaminants.

opencc-zeroDec 2017View details →

Data from: The pervasive effects of lighting environments on sensory drive in bluefin killifish: an investigation into male/male competition, female choice, and predation

Sensory drive predicts that the conditions under which signaling takes place have large effects on signals, sensory systems, and behavior. The coupling of an ecological genetics approach with sensory drive has been fruitful. An ecological genetics approach compares populations that experience different environments and asks whether population differences are adaptive and are the result of genetic and/or environmental variation. The multi-faceted effects of signaling environments are well-exemplified by the bluefin killifish. In this system, males with blue anal fins are abundant in tannin-stained swamps that lack UV/blue light but are absent in clear springs where UV/blue light is abundant. Past work indicates that lighting environments shape genetic and environmental variation in color patterns, visual systems, and behavior. Less is known about the selective forces creating the across population correlations between UV/blue light and the abundance of blue males. Here, we present three new experiments that investigate the roles of lighting environments on male competition, female mate choice, and predation. We found strong effects of lighting environments on male competition where blue males were more likely to emerge as dominant in tea-stained water than in clear water. Our preliminary study on predation indicated that blue males may be less susceptible to predation in tea-stained water than in clear water. However, there was little evidence for female preferences favoring blue males. The resulting pattern is one where the effects of lighting environments on genetic variation and phenotypic plasticity match the direction of selection and favor the expression of blue males in swamps.

opencc-zeroDec 2010View details →

Data from: Convergence of life history phenotypes in a Trinidadian killifish (Rivulus hartii)

Convergent evolution is characterized by the independent evolution of similar phenotypes within similar selective environments. Previous work on Trinidadian killifish, Rivulus hartii, demonstrated repeatable life history differences across communities that differ in predation intensity. These studies were performed in rivers located on the south slope of Trinidad's Northern Range Mountains. There exists a parallel series of rivers on the north slope of these mountains. As on the south slope, Rivulus is found across a gradient of fish predation. However, the predatory fish species in north-slope rivers are derived from marine families, whereas south-slope rivers contain a predatory fish fauna characteristic of the South American mainland. If predator-induced mortality and the associated indirect effects are the causal factors selecting for life history patterns in Rivulus, and these are similar in north and south-slope rivers, then the specific predatory species should be interchangeable and we would expect convergence of life history phenotypes across slopes. Here, we characterize the life history phenotypes of Rivulus from north-slope communities. We find similar patterns of life history divergence across analogous predator communities. Between slopes, minor differences in Rivulus life history traits exist and one potential cause of these differences is the abundance of Macrobrachium prawns in north-slope rivers.

opencc-zeroDec 2016View details →

Data from: The evolution of vertebrate eye size across an environmental gradient: phenotype does not predict genotype in a Trinidadian killifish

Vertebrates exhibit substantial variation in eye size. Eye size correlates positively with visual capacity and behaviors that enhance fitness, such as predator avoidance. This foreshadows a connection between predation and eye size evolution. Yet, the conditions that favor evolutionary shifts in eye size, besides the well-known role for light availability, are unclear. We tested the influence of predation on the evolution of eye size in Trinidadian killifish, Rivulus hartii. Rivulus are located across a series of communities where they coexist with visually oriented piscivores ('high predation' sites), and no predators ('Rivulus-only' sites). Wild-caught Rivulus from high predation sites generally exhibited a smaller relative eye size than communities that lack predators. Yet, such differences were inconsistent across rivers. Second-generation common garden reared fish revealed repeatable decreases in eye size in Rivulus from high predation sites. We performed additional experiments that tested the importance of light and resources on eye size evolution. Sites that differ in light or resource availability did not differ in eye size. Our results argue that differences in predator-induced mortality underlie genetically-based shifts in vertebrate eye size. We discuss the drivers of eye size evolution in light of the nonparallel trends between the phenotypic and common garden results.

FIGURE 3 in A new killifish genus and species from the coastal plains of northeastern Brazil (Teleostei: Cyprinodontiformes: Rivulidae)

FIGURE 3. Diagrammatic representation of the frontal squamation in: A, Rivulus and most annual fish genera, B, Prorivulus and Kryptolebias.

FIGURE 5 in A new killifish genus and species from the coastal plains of northeastern Brazil (Teleostei: Cyprinodontiformes: Rivulidae)

FIGURE 5. Phylogenetic relationships of basal rivulid lineages, according to synapomorphies established in Costa (2004a): clade A: unossified interhyal, absence of the distal process of the second epibranchial; clade B: Escales not overlaped, shortened uncinate process of the third epibranchial, articular face of the distal egde of the first hypobranchial anteriorly expanded, ventral process of the anguloarticular narrowed, posterior flange of the cleithrum absent.

FIGURE 4 in A new killifish genus and species from the coastal plains of northeastern Brazil (Teleostei: Cyprinodontiformes: Rivulidae)

FIGURE 4. Osteological features of some rivulids: left second epibranchial, ventrosagittal view: A, in Kryptolebias (sketch based on K. brasiliensis), B, in Prorivulus, Rivulus and all the annual rivulid genera (sketch based on Rivulus janeiroensis); left third epibranchial, ventrosagittal view: C, in Kryptolebias and Prorivulus (sketch based on K. brasiliensis), D, in Rivulus and all the annual rivulid genera (sketch based on Rivulus janeiroensis); left first hypobranchial, dorsal view: E, in Kryptolebias and Prorivulus (sketch based on K. brasiliensis), F, in Rivulus and all the annual rivulid genera (sketch based on Rivulus janeiroensis); left lower jaw, lateral view: G, in Kryptolebias and Prorivulus (sketch based on K. brasiliensis), H, in Rivulus and all the annual rivulid genera (sketch based on Cynolebias griseus Costa, Lacerda & Brasil); dorsal portion of left shoulder girdle, lateral view: I, in Kryptolebias and Prorivulus (sketch based on K. brasiliensis), J, in Rivulus and all the annual rivulid genera (sketch based on Trigonectes balzanii (Perugia)).

FIGURE 5 in Rivulus uatuman sp. n. (Teleostei: Cyprinodontiformes: Rivul idae): a new miniature killifish from the central Brazilian Amazon

FIGURE 5. Diagrammatic representation of the frontal squamation pattern and supraorbital neuromast arrangement in: A, Rivulus romeri, R. kirovskyi and R. uatuman (sketch based on R. kirovskyi, holotype, UFRJ 5935, male, 20.3 mm SL); and B, in other species of the genus (sketch based on R. santensis, UFRJ 123, male, 38.5 mm SL).