Testing climatic variability hypothesis in explaining elevational range distribution of moths

  • 黃 建宸

Student thesis: Master's Thesis

Abstract

Climatic variability hypothesis (CVH) proposed that organisms living at higher latitude or higher elevation experienced greater climatic variability and thus developed wider physiological thermal tolerance which enabled them to distribute widely Robustly testing CVH required empirical evidences of temperature variability species thermal traits and distribution ranges which were rarely available along single geographic gradient Here we tested CVH by using a species-rich taxa the Macromoths in subtropical mountains in Taiwan (around 24°N 121°E) Climatic loggers and light traps were set every 250 m along elevational transects to obtain climatic data and range distributions of moths Along the transects we set up thermal station to test critical thermal maximum (CTmax) or minimum (CTmin) temperatures of moths Our findings partly supported the predictions of CVH that there exists positive relationship between thermal tolerance and climatic variation However neither of climatic variation and species’ range sizes increase along elevational gradient In fact both CTmax and CTmin decreased with elevation but the slope of CTmax was steeper than that of CTmin which resulted in smaller thermal ranges in higher elevation Moreover both CTmax and CTmin were strongly affected by ambient temperature in the distribution midpoint of each species while both upper and lower limits were associated with CTmax The phenomenon contradicted previous findings that increasing climatic variation associated with wider thermal range of species along latitudinal gradients It suggested thermal adaptation of underlying macroecological pattern may differ in tropical ecosystems
Date of Award2017 Sep 12
Original languageEnglish
SupervisorI-Ching Chen (Supervisor)

Cite this

'