Life-History Variation Within a Population of the Colonial Ascidian Botryllus schlosseri. I. The Genetic and Environmental Control of Seasonal Variation

Evolution ◽  
1988 ◽  
Vol 42 (5) ◽  
pp. 900 ◽  
Author(s):  
Richard K. Grosberg
Keyword(s):  
Life History ◽  
Seasonal Variation ◽  
Environmental Control ◽  
Botryllus Schlosseri ◽  
Life History Variation ◽  
Colonial Ascidian

scholarly journals Life histories as mosaics: plastic and genetic components differ among traits that underpin life-history strategies

2021 ◽  
Author(s):  
Anja Felmy ◽  
David N. Reznick ◽  
Joseph Travis ◽  
Tomos Potter ◽  
Tim Coulson
Keyword(s):  
Life History ◽  
Life Histories ◽  
Environmental Control ◽  
Relative Strength ◽  
Life History Strategies ◽  
Life History Variation ◽  
Genotype By Environment Interactions ◽  
Genotype By Environment ◽  
Genetic Components ◽  
Genes And Environment

AbstractLife-history variation reflects phenotypic variation across suites of traits. Differences among life-history strategies result from genetic differentiation, phenotypic plasticity, and genotype-by-environment interactions. If the relative strength and direction of these components differed among traits underlying a strategy, life histories might not evolve as a cohesive unit.We tested this hypothesis on the high- and low-predation ecotypes of Trinidadian guppies, defined by distinct life-history strategies. Using common garden experiments, we assessed how strongly 36 traits were determined by ancestral habitat (i.e., ecotype) or food availability, a key environmental difference between ecotypes. Our dataset was large (1178 individuals) and included six putatively independent origins of the derived ecotype.Traits could be confidently assigned to four groups, defined by highly significant effects of only food (13 traits), only habitat (6), both (6), or neither (11), revealing substantial variation among traits in levels of genetic and environmental control. Ecotype-food (i.e., genotype-by-environment) interactions were negligible. The directions of plastic and genetic effects were usually aligned.This suggests that life histories are mosaics with unequal rates of phenotypic and evolutionary change. Broadly speaking of “life-history evolution” masks a complex interplay of genes and environment on the multiple traits that underpin life-history strategies.

Three sibling species of didemnid ascidians from northern Norway: Didemnum albidum (Verrill, 1871), Didemnum polare (Hartmeyer, 1903), and Didemnum romssae sp.nov.

1996 ◽  
Vol 74 (2) ◽  
pp. 357-379 ◽  
Author(s):  
Jessica A. Marks
Keyword(s):  
Life History ◽  
Sibling Species ◽  
Distinct Species ◽  
Morphological Characters ◽  
Reticulate Evolution ◽  
Life History Variation ◽  
Larval Size ◽  
Colonial Ascidian ◽  
Northern Norway ◽  
Didemnid Ascidians

Recent advances in taxonomy have disclosed the prevalence of cryptic sibling species in marine systems. In didemnid ascidians, morphological variation between species is often slight, and many species may have been overlooked. Species boundaries within this group are often equivocal, and patterns among taxa are reminiscent of those formed by reticulate evolution in plants. Specimens of the sessile colonial ascidian Didemnum albidum (Verrill, 1871) were examined for life-history and morphological characters and found to constitute at least three sympatric sibling species. One of these, Didemnum romssae, is described here as a new species. Colonies were collected from hard-bottom assemblages in Troms and Finnmark counties in northern Norway. Zooid morphology in D. romssae is similar to that of D. albidum, but varies within each species, even for traits usually considered specific. Didemnum romssae is proposed as a distinct species on the basis of consistent differences in (i) the shape and size of calcium carbonate spicules within the common test; (ii) larval size and the number of lateral ampullae; (iii) timing of reproduction; and (iv) the absence of a seasonal nonfeeding, overwintering stage, which occurs in D. albidum. Examination of specimens from museum collections considered synonymous with D. albidum confirmed the presence of a third species, Didemnum polare (Hartmeyer, 1903), which differed from the other two species in zooid and larval morphology as well as spicule shape. Complexes of sibling species such as these provide a tractable system for studying the consequences of life-history variation among closely related taxa.

scholarly journals Life history and ecological genetics of the colonial ascidian Botryllus schlosseri

2015 ◽  
Vol 257 ◽  
pp. 54-70 ◽  
Author(s):  
Francesca Cima ◽  
Loriano Ballarin ◽  
Federico Caicci ◽  
Nicola Franchi ◽  
Fabio Gasparini ◽  
...  
Keyword(s):  
Life History ◽  
Ecological Genetics ◽  
Botryllus Schlosseri ◽  
Colonial Ascidian
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