scholarly journals Parallel and non-parallel divergence within polymorphic populations of brook stickleback, Culaea inconstans (Actinopterygii: Gasterosteidae)

2021 ◽  
Author(s):  
Kaitlyn Willerth ◽  
Emily Franks ◽  
Jonathan A Mee
Keyword(s):  
Adaptive Evolution ◽  
Parallel Evolution ◽  
Threespine Stickleback ◽  
Ecological Consequences ◽  
Spine Morphology ◽  
Culaea Inconstans ◽  
Body Morphology ◽  
Selective Pressures ◽  
Brook Stickleback ◽  
Littoral Habitats

Studying parallel evolution allows us to draw conclusions about the repeatability of adaptive evolution. Whereas populations likely experience similar selective pressures in similar environments, it is not clear if this will always result in parallel divergence of ecologically relevant traits. Our study investigates the extent of parallelism associated with the evolution of pelvic spine reduction in brook stickleback populations. We find that populations with parallel divergence in pelvic spine morphology do not exhibit parallel divergence in head and body morphology but do exhibit parallel divergence in diet. In addition, we compare these patterns associated with pelvic reduction in brook stickleback to well-studied patterns of divergence between spined and unspined threespine stickleback. Whereas spine reduction is associated with littoral habitats and a benthic diet in threespine stickleback, spine reduction in brook stickleback is associated with a planktonic diet. Hence, we find that pelvic spine divergence is associated with largely non-parallel ecological consequences across species.

scholarly journals Parallel evolution of sperm hyper-activation Ca2+ channels

2017 ◽  
Author(s):  
Jacob C. Cooper ◽  
Nitin Phadnis
Keyword(s):  
Molecular Evolution ◽  
Adaptive Evolution ◽  
Parallel Evolution ◽  
Channel Activity ◽  
Polycystic Kidney ◽  
Reproductive Proteins ◽  
Parallel Patterns ◽  
Selective Pressures ◽  
Sperm Flagellum ◽  
Ca2 Channels

AbstractSperm hyper-activation is a dramatic change in sperm behavior where mature sperm burst into a final sprint in the race to the egg. The mechanism of sperm hyper-activation in many metazoans, including humans, consists of a jolt of Ca2+ into the sperm flagellum via CatSper ion channels. Surprisingly, CatSper genes have been independently lost in several animal lineages. In Drosophila, sperm hyper-activation is performed through the co-option of the polycystic kidney disease 2 (Dpkd2) Ca2+ channel. The parallels between CatSpers in primates and Dpkd2 in Drosophila provide a unique opportunity to examine the molecular evolution of the sperm hyper-activation machinery in two independent, nonhomologous calcium channels separated by more than 500 million years of divergence. Here, we use a comprehensive phylogenomic approach to investigate the selective pressures on these sperm hyper-activation channels. First, we find that the entire CatSper complex evolves rapidly under recurrent positive selection in primates. Second, we find that pkd2 has parallel patterns of adaptive evolution in Drosophila. Third, we show that this adaptive evolution of pkd2 is driven by its role in sperm hyper-activation. These patterns of selection suggest that the evolution of the sperm hyper-activation machinery is driven by sexual conflict with antagonistic ligands that modulate channel activity. Together, our results add sperm hyper-activation channels to the class of fast evolving reproductive proteins and provide insights into the mechanisms used by the sexes to manipulate sperm behavior.

scholarly journals Assessing evidence for adaptive evolution in two hearing-related genes important for high-frequency hearing in echolocating mammals

2021 ◽  
Author(s):  
Hui Wang ◽  
Hanbo Zhao ◽  
Yujia Chu ◽  
Jiang Feng ◽  
Keping Sun
Keyword(s):  
Adaptive Evolution ◽  
Hair Cells ◽  
High Frequency ◽  
Phylogenetic Trees ◽  
Outer Hair Cells ◽  
Functional Domain ◽  
Coding Region ◽  
Selective Pressures ◽  
Wide Range ◽  
Different Parts

Abstract High-frequency hearing is particularly important for echolocating bats and toothed whales. Previously, studies of the hearing-related genes Prestin, KCNQ4, and TMC1 documented that adaptive evolution of high-frequency hearing has taken place in echolocating bats and toothed whales. In this study, we present two additional candidate hearing-related genes, Shh and SK2, that may also have contributed to the evolution of echolocation in mammals. Shh is a member of the vertebrate Hedgehog gene family and is required in the specification of the mammalian cochlea. SK2 is expressed in both inner and outer hair cells, and it plays an important role in the auditory system. The coding region sequences of Shh and SK2 were obtained from a wide range of mammals with and without echolocating ability. The topologies of phylogenetic trees constructed using Shh and SK2 were different; however, multiple molecular evolutionary analyses showed that those two genes experienced different selective pressures in echolocating bats and toothed whales compared to non-echolocating mammals. In addition, several nominally significant positively selected sites were detected in the non-functional domain of the SK2 gene, indicating that different selective pressures were acting on different parts of the SK2 gene. This study has expanded our knowledge of the adaptive evolution of high-frequency hearing in echolocating mammals.

Geographic and morphological variation in the presence and absence of the pelvic skeleton in the brook stickleback, Culaea inconstans (Kirtland), in Alberta and Saskatchewan

1971 ◽  
Vol 49 (3) ◽  
pp. 343-352 ◽  
Author(s):  
Joseph S. Nelson ◽  
F. Mervyn Atton
Keyword(s):  
Morphological Variation ◽  
Fishery Management ◽  
Fish Introduction ◽  
Spine Length ◽  
Culaea Inconstans ◽  
Full Development ◽  
Normal Individuals ◽  
Brook Stickleback ◽  
Presence And Absence ◽  
Skeleton Formation

Brook sticklebacks, Culaea inconstans (Kirtland), are known from 20 locations in Alberta and Saskatchewan in which a high proportion of the individuals lack all or part of the pelvic skeleton. These locations are interspersed and surrounded by other locations containing individuals with a normal pelvic skeleton. Individuals which lack the skeleton are of both sexes and are fertile in at least one of the lakes.Considerable variation exists between locations in the proportion of individuals with and without the pelvic skeleton. Morphological intermediates are known from most of the 20 locations and virtually all degrees of pelvic skeleton formation exist between its absence and its full development. Little or no gradation exists, however, in pelvic spine length between their absence and presence. Although the pelvic spines are the first part of the pelvic skeleton to appear during ontogeny, they are present only in intermediates with a virtually complete skeleton base. In addition, many intermediates are highly asymmetrical in their pelvic skeleton while development during the ontogeny of normal individuals is symmetrical.There is a greater tendency for individuals in which the pelvic skeleton is deficient to occur in lakes which lack an outlet rather than to occur in lakes with a permanent outlet. An unusually high proportion of the lakes with these aberrant individuals have been subject to fishery management activities (fish introduction and poisoning), but these disturbances are not causing the loss of the pelvic skeleton.

scholarly journals Hitchhiking and epistasis give rise to cohort dynamics in adapting populations

2017 ◽  
Vol 114 (31) ◽  
pp. 8330-8335 ◽  
Author(s):  
Sean W. Buskirk ◽  
Ryan Emily Peace ◽  
Gregory I. Lang
Keyword(s):  
Adaptive Evolution ◽  
Driving Force ◽  
Parallel Evolution ◽  
Low Frequency ◽  
Target Size ◽  
Driver Mutations ◽  
Beneficial Mutations ◽  
Large Target ◽  
Asexual Populations ◽  
Comprehensive Study

Beneficial mutations are the driving force of adaptive evolution. In asexual populations, the identification of beneficial alleles is confounded by the presence of genetically linked hitchhiker mutations. Parallel evolution experiments enable the recognition of common targets of selection; yet these targets are inherently enriched for genes of large target size and mutations of large effect. A comprehensive study of individual mutations is necessary to create a realistic picture of the evolutionarily significant spectrum of beneficial mutations. Here we use a bulk-segregant approach to identify the beneficial mutations across 11 lineages of experimentally evolved yeast populations. We report that nearly 80% of detected mutations have no discernible effects on fitness and less than 1% are deleterious. We determine the distribution of driver and hitchhiker mutations in 31 mutational cohorts, groups of mutations that arise synchronously from low frequency and track tightly with one another. Surprisingly, we find that one-third of cohorts lack identifiable driver mutations. In addition, we identify intracohort synergistic epistasis between alleles of hsl7 and kel1, which arose together in a low-frequency lineage.

scholarly journals Solitary ecology as a phenomenon extending beyond insular systems: exaptive evolution in Anolis lizards

2019 ◽  
Vol 15 (5) ◽  
pp. 20190056 ◽  
Author(s):  
Julián A. Velasco ◽  
Steven Poe ◽  
Constantino González-Salazar ◽  
Oscar Flores-Villela
Keyword(s):  
Body Size ◽  
Adaptive Evolution ◽  
Environmental Filtering ◽  
Phenotypic Evolution ◽  
Phenotypic Differentiation ◽  
Evolutionary Transitions ◽  
Ecological Release ◽  
Selective Pressures ◽  
Island Species

The mechanisms driving phenotypic evolution have been of interest to biologists since Darwin. Ecological release—wherein adaptive evolution occurs following relaxation of constraining selective pressures—and environmental filtering—wherein exaptive traits allow colonization of a new area—have been studied in several insular cases. Anolis lizards, which may exist in solitude or sympatry with multiple congeners, are an excellent system for evaluating whether ecological release and environmental filtering are associated with phenotypic shifts across phylogenetic and geographical scales. Insular solitary Anolis exhibit phenotypic differentiation in body size and sexual size dimorphism—SSD—through exaptive and adaptive evolution, respectively. But, the generality of these effects has not yet been addressed. Here, we analyse the evolution of body size and SSD relative to sympatry in mainland Anolis . We found that mainland species co-occurring with few congeners exhibit uniform body size and greater SSD relative to other random mainland assemblages, consistent with the insular solitary pattern. The locations of evolutionary shifts for both traits do not coincide with evolutionary transitions to decreased levels of sympatry. These results are consistent with exaptive environmental filtering but not adaptive ecological release. Future studies should be conducted at local scales to evaluate the role of these factors in the evolution of solitary existence in mainland and island species.

Geographic Variation in the Brook Stickleback, Culaea inconstans, and Notes on Nomenclature and Distribution

1969 ◽  
Vol 26 (9) ◽  
pp. 2431-2447 ◽  
Author(s):  
Joseph S. Nelson
Keyword(s):  
Geographic Variation ◽  
Northwestern Part ◽  
Clinal Variation ◽  
Body Depth ◽  
Spine Length ◽  
Culaea Inconstans ◽  
Dorsal Fin ◽  
Fin Rays ◽  
Historical Origin ◽  
Brook Stickleback

Clinal variation in dorsal and pelvic spine lengths was observed in the brook stickleback, Culaea inconstans, in an examination of 1366 specimens from 62 localities. Mean spine length was longest in the Wisconsin to Ohio area and generally decreased to the west, north, and east of this area. Shortest spines were observed in the northwestern part of the range of the species. A population in New Mexico, believed to be relict, was highly variable, but most specimens had long spines. Pelvic spines, and the supporting skeleton, were absent in most specimens from five localities in Alberta. Pelvic skeleton size and body depth were generally greatest in the area east of Wisconsin and least in the northwestern part of the range. Although C. inconstans is generally described as being naked, a series of about 30–36 small bony scutes was found along the lateral line in all populations examined. No marked geographic variation was observed in number of pectoral rays, caudal rays, soft dorsal-fin rays, soft anal-fin rays, gill rakers, scutes, or vertebrae. The nomenclature and distribution of C. inconstans are reviewed. The historical origin of clinal variation in spine length is discussed.

Unusual Occurrence of the Brook Stickleback (Culaea inconstans) in the Mackenzie River, Northwest Territories

1972 ◽  
Vol 29 (11) ◽  
pp. 1655-1656 ◽  
Author(s):  
M. R. Falk
Keyword(s):  
Northwest Territories ◽  
Red River ◽  
The South ◽  
Culaea Inconstans ◽  
Resident Population ◽  
Great Slave Lake ◽  
Unusual Occurrence ◽  
South Shore ◽  
Brook Stickleback ◽  
Mackenzie River

Two specimens of the brook stickleback (Culaea inconstans) were taken in the mouths of Pierre and Tsital Trien creeks near Arctic Red River on the Mackenzie River during 1971. Previous most northerly published records were from the south shore of Great Slave Lake. The specimens may have been carried downstream by spring floods and may not represent a resident population.

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