Reproductive biology of the onychophoran Euperipatoides rowelli

Abstract

The reproductive biology of the ovoviviparous peripatus Euperipatoides rowelli was investigated from ®eld collections and laboratory cultures. The sexes have different demographics. The frequency distribution of individual weight is essentially L-shaped in females, but closer to normality for males: thus the sexes must exhibit different patterns of growth and/or mortality. Males are generally much smaller and rarer than females. The primary sex ratio seems to be 1:1 with equal investment in the sexes, while the tertiary ratio is highly female-biased. Logs with fewer individuals tend to be male-biased while well-populated logs tend to be female-biased. Males mature at 15±30% of the bodyweight of mature females. The weight frequency distribution of males without developed sperm in their tracts is strongly skewed to the lower weights, while that of males with sperm is more normally distributed, indicating that sperm production occurs as soon in life as possible. Males mature in their ®rst year of life, if growth rates in culture may be extrapolated to the wild. In contrast to this rapid maturity in males, females may mature as late as their second or third years. Most mature females, and many prior to maturity, carry sperm in their spermathecae. After maturity, there is an approximately linear relationship between body mass and number of developing embryos. Reproduction in E. rowelli is signi®cantly seasonal despite high individual variance, with a major bout of parturition in November±December (summer). A female can harbour one developed and one undeveloped batch of embryos in each uterus. Excesses of developed embryos in one uterus are counterbalanced by de®cits of undeveloped ones, indicating that females can use their paired reproductive tracts independently. Individual females in culture can experience episodes of parturition approx. 6 months apart without re-mating, thus gestation may be 6 months or more. Sperm in spermathecae remain capable of vigorous swimming for at least 9.5 months.

Unexplored Character Diversity in Onychophora (Velvet Worms): A Comparative Study of Three Peripatid Species

“…On average, each cultured female gave birth to 20–40 young during the entire lifespan, which can exceed five years. The number of males and females born in our cultures was equal, whereas the ratio of collected males to females was 1 to 4, as reported for other species of Peripatidae [53] and Peripatopsidae [54]–[56].…”

Environmental Complexity and Biodiversity: The Multi-Layered Evolutionary History of a Log-Dwelling Velvet Worm in Montane Temperate Australia

“… 1 M13 tail concatenated to 5’ end of each forward primer for use in visualising not shown. 2 New locus designed during this study from 454 pyrosequencing data 3 Redesigned versions of primers for loci described in Sunnucks & Wilson [14] which give improved performance.…”

“… 3 Redesigned versions of primers for loci described in Sunnucks & Wilson [14] which give improved performance.…”

“…A notable and recurring pattern is evidence of phylogeographic regions that are broadly concordant across organisms encompassing a range of dispersal abilities and life histories [12,13]. These include Onychophora (velvet worms), including the species studied here [14,15], terrestrial Platyhelminths (flatworms) [13], Collembola (springtails) [4,12,16], funnel-web spiders [6,17], and skinks [7]. The phylogeographic regions identified correspond approximately but variably to five microgeographic regions proposed in Garrick et al [4], which in turn are associated with topography and other environmental gradients that may have generated long-standing barriers to gene flow in saproxylic and forest-floor species [5,18].…”

“…Euperipatoides rowelli is distributed over much of southern New South Wales, including Tallaganda, although morphological, chromosomal and genetic data indicate this range almost certainly includes multiple cryptic taxa [14,21,22]. Within Tallaganda, there is some evidence of life history differentiation among forms in different microgeographic regions [23], and morphologically aberrant individuals indicative of hybrid breakdown are found where at least one pair of regions meet [24]. Like most Australian Onychophora, E. rowelli is saproxylic and a predator of small invertebrates.…”