EYESPOT TRAITS OF NYMPHALID BUTTERFLIES UNDER CLIMATE CHARACTERISTICS AND PREDATION PRESSURE

  • 姜 信宏

Student thesis: Doctoral Thesis

Abstract

Wing patterns in Lepidopteran play important roles in predation avoidance thermal adaptation and sexual selection Among wing color patterns the eyespot is a conspicuous trait with a complicated color structure Eyespots have attracted biologists to explore its functions and fitness for a hundred years Past studies have pointed out that the eyespot traits such as number size and color contrast are mainly used to cope with predation pressure In addition to predation pressure abiotic factors (such as temperature precipitation and seasonality) may affect eyespots as their proximate cause However most studies have examined the anti-predator strategy with conspicuous eyespot traits but rarely test the relation between eyespot variation and factors across species at large spatial scale The eyespot trait variations along predation or environmental gradients are still unknown This study collected the global open database from The Global Biodiversity Information Facility (GBIF) Symbiota Collections of Arthropods Network (SCAN) Integrated Digitized Biocollections (iDigBio) and Barcorde of Life Data (BOLD) for 993 species in Nymphalidae more than 45 000 specimen digital images The convolutional neural network was used to quantify the number of eyespots the ratio of the max eyespot size the ratio of total eyespot size eyespot color contrasts between eyespots and wings and eyespot color contrasts within eyespots We then used hierarchical partitioning and structural equation model to examine how temperature precipitation productivity and predation pressure (using the richness of insectivorous birds as an indicator) explain eyespot variation directly and indirectly We found that predation pressure mainly affected the colour contrast of eyespot rather than the size and number Importantly temperature seasonality diurnal temperature range and the mean temperature in the coldest quarter mainly and significantly affected eyespot number size and contrast separately Our findings indicate that predation pressure effectively selected for high contrast of eyespots across wide variety of Nymphalid butterflies However climate and its variation play more important roles in determine eyespot variations at global scale and the underlying mechanisms are to be explored Our study provides evidence of how eyespots vary with predation pressure and climate factors globally and paves new avenue of related studies in macroecology of eyespot variation
Date of Award2021
Original languageEnglish
SupervisorI-Ching Chen (Supervisor)

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