It is good practice to fully understand components of an ecosystem if we hope to preserve its biodiversity. A problem is that we know very little about some organisms and nothing of others. Studies that investigate an organism’s basic biological, ecological and physiological life history variables advance our knowledge of the species of interest and also offer insight about community structure and function. In this thesis I explore courtship behaviors, metamorphic tendencies and hematological parameters in two species of Dicamptodon salamanders (D. copei and D. tenebrosus).
Ecologists examine blood to assess hematological responses to a plethora of factors including hormonal changes, parasites, reproductive status and environmental stressors. While hematologic principles are fairly conserved in vertebrates, blood tissue has evolved to match the organism with its environment and there is considerable diversity in hematological parameters across taxa. Therefore, it is necessary to collect species specific baseline data for comparison. In Chapter 2, I quantified relative white blood cells and erythrocyte dry volume measurements of both D. tenebrosus and D. copei in the wild and in captivity. No prior studies have evaluated the hematological parameters of Dicamptodon salamanders. My investigation revealed similar leukocyte ratios between species and between wild and captive D. tenebrosus, while leukocyte ratios of wild and captive D. copei were significantly different.
Dicamptodon species and populations vary in metamorphic tendencies though the reasons for this variation are not known. In Chapter 3 I investigated the difference in metamorphic tendencies of D. copei and D. tenebrosus. First, I tested the hypotheses that high water inhibits and thermal stress induces metamorphosis. Neither lowered water, nor increased aquatic temperatures induced metamorphosis. Secondly, I compared thermal preferences of both species and found differences in the selection tendencies between species and between sizes of both species. Lastly, I stress responses of both species to 1.66º C, 21.11 º C and 25º C water using a hematological approach. This study revealed significant differences in hematological stress indices between the two species.
In Chapter 4, I explored the courtship behaviors of D. copei and D. tenebrosus and characterized each behavior and temporal pattern, using a phyloethological approach. I then compared these courtship behaviors between species and to that of the nearest salamander family, Ambystomatidae. The courtship patterns and behaviors were similar in both species, but they did not resemble the courtship patterns or behaviors of their sister taxon, Ambystoma.