Intrinsic and Extrinsic Factors Mediating the Expression of Alternative Mating Tactics in Male Green Treefrogs, Hyla Cinerea

Liddell, Aleah R. (2016) Intrinsic and Extrinsic Factors Mediating the Expression of Alternative Mating Tactics in Male Green Treefrogs, Hyla Cinerea. Undergraduate thesis, under the direction of Christopher Leary from Biology, University of Mississippi.

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Abstract

Males of many anuran species optimize their chances of reproductive success by vigorously calling to attract females or by adopting a non-calling “satellite” mating tactic. Satellite males perch silently near calling males and attempt to intercept females that the caller attracts. Models predict that tactic expression in male anurans is influenced by either extrinsic factors (i.e., the social-acoustic environment) or intrinsic factors (i.e., circulating hormone levels and body condition), but it is unclear how these factors potentially interact to influence tactic expression. For example, males often adopt a satellite mating tactic in response to the broadcast vocalizations of conspecific males, suggesting that males make mating tactic decisions based on the relative attractiveness of nearby calling males. However, the responses of males to broadcast vocalizations are often highly variable, suggesting that the physiological status of males may also be a primary factor influencing tactic decisions under varying social-acoustic contexts. For example, recent models show that an increase in circulating glucocorticoids and a decrease in circulating androgens associated with the depletion of energy reserves during vocalization mediate transitions from calling to non-calling behavior in anurans. To examine how the social-acoustic environment and physiological status of males potentially interact to influence mating tactic decisions, I broadcast calls to calling male green treefrogs, Hyla cinerea, in natural choruses and observed whether males continued to call or adopted a non-calling satellite mating tactic. I then acquired blood samples and measured the size and weight of males to assess whether the probability that a male remained a caller or switched to a non-calling satellite mating tactic was influenced by circulating hormone levels and/or relative body condition. I found that males that continued to call and males that adopted a non-calling satellite tactic in response to broadcast calls did not differ in circulating hormone levels. However, males that continued to call were generally larger, heavier, and in better condition than non-callers. Males that continued to call also produced longer, lower-frequency calls and invested more energy in calling. My results suggest that mating tactic expression in H. cinerea is determined by relative vocal attractiveness and that vocal quality is influenced by size, weight, and body condition.

Item Type: Thesis (Undergraduate)
Uncontrolled Keywords: This is a thesis that centers on the exploration of factors that influence mating tactic expression in green treefrogs, Hyla cinerea.
Creators: Liddell, Aleah R.
Student's Degree Program(s): B.S. in Biological Science
Thesis Advisor: Christopher Leary
Thesis Advisor's Department: Biology
Institution: University of Mississippi
Subjects: Q Science > QL Zoology
Depositing User: Miss Aleah Liddell
Date Deposited: 16 May 2016 13:16
Last Modified: 16 May 2016 13:16
URI: http://thesis.honors.olemiss.edu/id/eprint/609

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