assessment-mitochondrial-oxygen-consumption-using-plate-reader-based

Assessment of Mitochondrial Oxygen Consumption Using a Plate Reader-based Fluorescent Assay

Mitochondria serve many important functions, including cellular respiration, ATP production, controlling apoptosis, and acting as a central hub of ...

Elon University

Isolation due to both geological barriers and range contractions during the Pleistocene glacial maxima has been an important cause of diversification of arid-adapted species in the North American deserts. Tree lizards, Urosaurus ornatus, are distributed across much of the southwestern arid regions and can tolerate a wide range of environments. Thus, they may have avoided large-scale shifts in distribution caused by Pleistocene climate change and any subsequent evolutionary impacts. Cytochrome b sequences were sampled from U. ornatus across the northern part of their range to test if current structure of these populations resulted from post-Pleistocene range expansion and habitat fragmentation, or prior geological isolation. Phylogenetic analyses found geographical structuring of populations consistent with a model of long-term geographical isolation corresponding to each of the desert regions. The two post-Pleistocene hypotheses were not well supported as estimated times of divergence predated the retreat of the last continental ice sheet. Populations in different regions were impacted by different processes. Southern populations of U. ornatus appear to have remained largely independent of more derived northern and eastern populations during Pleistocene climate change, while populations in regions containing more derived populations showed evidence of more recent range expansion (Colorado Plateau). As populations of U. ornatus attest to, the complex and dynamic history of the southwestern USA has left a deep-rooted and multifaceted imprint on genetic and phylogeographical structure of the species living there.

Phylogeography of the tree lizard, Urosaurus ornatus: responses of populations to past climate change.

Tree lizards (Urosaurus ornatus) are a highly accessible species useful in testing theories of life-history evolution and behavioural ecology. A polymerase chain reaction-based method was used to isolate nine polymorphic tetranucleotide microsatellite loci from the genome of these lizards. The isolated loci displayed 5 to 9 alleles in the populations screened. Observed heterozygosity ranged from 0.333 to 0.900. Results indicate these loci now provide a basis to study mate choice, parentage, and population genetic structure within this species.

Isolation and characterization of microsatellite markers in tree lizards (Urosaurus ornatus).

Introgression of mtDNA appears common in animals, but the implications of acquiring a novel mitochondrial genome are not well known. This study investigates mito-genome introgression between the lizard species Urosaurus graciosus, a thermal specialist, and U. ornatus, a species that occupies a wider range of thermal environments. As ectotherms, their metabolic rate is strongly influenced by the thermal environment; with mitochondria being linked to metabolic rates, overall energy budgets could be impacted by introgression. I use mitochondrial gene trees, inferred from Bayesian analyses of Cyt-B and ND1 gene sequences, along with morphology and microsatellites from nineteen populations of these two species to address if the direction and location of mito-nuclear discordance match predictions of introgression resulting from past population expansions. MtDNA is expected to move from resident species into expanding or invading species. Second, does having a heterospecific form of mitochondria impact body size, a trait strongly associated with fitness? Multiple independent introgression events of historic origin were detected. All introgression was unidirectional with U. ornatus-type mtDNA found in U. graciosus parental type individuals. This result was consistent with population expansions detected in U. graciosus but not U. ornatus. Females with heterospecific mtDNA were significantly smaller than homospecific forms, and heterospecific males had a different relationship of body mass to body length than those with homospecific mtDNA. These changes indicate a potential selective disadvantage for individuals with heterospecific mitochondria and are consistent with the theoretical expectation that deleterious alleles are more likely to persist in expanding populations.

Article	Year
Phylogeography of the tree lizard, Urosaurus ornatus: responses of populations to past climate change. Molecular ecology\| PubMed ID: 17868290	2007
Isolation and characterization of microsatellite markers in tree lizards (Urosaurus ornatus). Molecular ecology resources\| PubMed ID: 21564702	2009
Introgression of mtDNA in Urosaurus lizards: historical and ecological processes. Molecular ecology\| PubMed ID: 27864892	2017

Gregory Haenel

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