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BIOL 1902 Lecture Notes - Lecture 9: Gray Tree Frog, Alpheidae, Phenotypic Plasticity

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viridianlouse961
19 Apr 2016
School
Carleton University
Department
Biology
Course
BIOL 1902
Professor
Michael Runtz

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Document Summary

Mechanisms of speciation (read up in textbook) From a view or evolution: smallest evolutionary independent unit. Biological species concept according to biological standpoints different species are two animals who cannot interbreed. For a-sexual species the biological species cannot be used as it does not take two organisms to create more organisms. In this case the physical differences are what defines the different species. One problem: criteria used to make this decision is that the people who decide how. Different the individual organisms must be to be considered different is a little arbitrary. But for the most part these a-sexual species are differentiated as different species based on their morphological characteristics. Species decided based on differences in their dna. It is mostly decided based on their populations and where they live. Their species is typically decided on any common traits from their ancestors. (the number of nodes from the original organism can distinguish how closely related the organisms are)

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Related Questions

Of the following sets of species, state which species definition (morphological, phylogenetic, or biological) best applies

a. Species boundaries in many tiny organisms, such as Oligotrich ciliates that live in the ocean, are determined using features that are visible under a light microscope.

b. Two wild relatives of lettuce, Lactuca canadensis and Lactuca graminifolia, produce flowers at different times – L. canadensisflowers in summer and L. graminifolia flowers in early spring.

c. As their names suggest, spring field crickets (Gryllus veletis) mature and become reproductively active in the spring, while fall field crickets (Gryllus pennsylvanicus) mature and reproduce in the fall.

d. Several closely-related (and very similar-looking) species of fungus in the genus Wallemia were identified using an evolutionary tree based on DNA sequences from several genes.

e. The breeding season for the red-legged frog (Rana aurora) occurs between January and March, while the breeding season of its close relative (Rana boylii) lasts from March through May.

f. Analysis of evolutionary relationships among several species of crayfish in the genus Pacifastacus were used to distinguish species from one another, and to identify species of possible conservation concern.

4. The shovel-nosed salamander, Desmognathus marmoratus, is a totally aquatic, endemic species found in high mountain streams in the Appalachian Mountains of Tennessee, North Carolina, South Carolina and Georgia. No gene flow occurs between river drainages due to the completely aquatic lifestyle of this salamander. Populations on either side of the Tennessee Divide (Tennessee and N. Carolina vs. Georgia and S. Carolina) have no morphological differences between them. A phylogeny based on mtDNA sequences (Jones et al. 2006) showed, however, that populations on either side of the Tennessee Divide showed greater than 14% sequence divergence and were well supported, separate, monophyletic lineages. Salamanders collected from drainages on both sides of the Tennessee Divide were brought into the laboratory and observations confirmed that salamanders from Tennessee would mate with salamanders from Georgia and made viable and fertile F1 and F2 offspring. Based upon your understanding of different species concepts (biological, morphospecies, phylogenetic), how would each classify these shovel-nosed salamanders (i.e., separate species or the same species, and why?). Under which type/mode of speciation are these salamanders likely to be diverging on opposite sides of the Tennessee Divide?

4. The shovel-nosed salamander, Desmognathus marmoratus, is a totally aquatic, endemic species found in high mountain streams in the Appalachian Mountains of Tennessee, North Carolina, South Carolina and Georgia. No gene flow occurs between river drainages due to the completely aquatic lifestyle of this salamander. Populations on either side of the Tennessee Divide (Tennessee and N. Carolina vs. Georgia and S. Carolina) have no morphological differences between them. A phylogeny based on mtDNA sequences (Jones et al. 2006) showed, however, that populations on either side of the Tennessee Divide showed greater than 14% sequence divergence and were well supported, separate, monophyletic lineages. Salamanders collected from drainages on both sides of the Tennessee Divide were brought into the laboratory and observations confirmed that salamanders from Tennessee would mate with salamanders from Georgia and made viable and fertile F1 and F2 offspring. Based upon your understanding of different species concepts (biological, morphospecies, phylogenetic), how would each classify these shovel-nosed salamanders (i.e., separate species or the same species, and why?). Under which type/mode of speciation are these salamanders likely to be diverging on opposite sides of the Tennessee Divide?