Reproductive modes in Sichuan anurans

Abstract

A total of 94 anuran species have been recorded in Sichuan Province, China. Among these species, there are five different reproductive modes belonging to two major categories according to Duellman & Trueb’s (1986) definition. The most common (93%, 68 of 73 species) site type of oviposition is free moving water, including both lentic water (mode 1) and lotic water (mode 2), which have been considered to be the primitive modes of reproduction in anurans. The deposition of eggs out of water includes terrestrial nests near water (mode 12), terrestrial foam nests in burrows or depressions (mode 21), and arboreal foam nests on trees and bushes over ponds or streams (mode 23). Species using modes 1, 12, 21, and 23 have smaller body sizes and deposit larger clutch sizes with smaller ovum diameter than those species using mode 2. Tadpoles of the former species inhabit non-flowing water systems and develop quickly; these tadpoles have small body sizes and short tails. Species using mode 2 have large body size, produce small clutch sizes with large ovum diameter. Their tadpoles inhabit flowing water systems and require a long development time; these tadpoles have large body size and long tails. The species using mode 1 exhibit a r-selected strategy by producing small-yolked eggs, investing less energy in each egg, and increasing clutch size. Conversely, the species using mode 2 produce large-yolked eggs, invest more energy per egg, and show a reduction in the number of eggs, which is characteristic of a k-selected strategist.