The life cycle of a desert spider inferred from observed size frequency distribution

Abstract

We studied the life cycle of the spider Syspira tigrina (Araneae: Miturgidae) by indirect methods. This species is endemic to the North American deserts and locally abundant; nevertheless, information on its biology is scarce. We did monthly collections for over a year at La Paz, Baja California Sur, Mexico. We found that adult spiders were more abundant between August and November 2005 and had low abundance or were absent the remainder of the year while juveniles were present all year. To estimate changing body size structure of the population we analyzed juvenile tibia I length distribution (TIL) (as indicator of the body size) of each monthly sample by means of Kernel Density Estimators (KDEs). We found 35 TIL juveniles size groups (Gaussian components). The smallest juveniles were more abundant between October 2005 and January 2006 and the biggest were more abundant twice during the hottest months. We hypothesize that mating period is between August and October 2005 and the main recruitment period from November 2005 and January 2006. However we found evidenceof continuous recruitment through the year, suggesting that although there is a peak of reproduction in November, the females oviposit almost all year. Also there is evidence of juveniles’ growth pattern from January to July 2006. The use of KDEs with histograms is a very good statistical tool to delimit size groups with mixed frequency distributions that otherwise might be difficult. This tool should be useful to test any hypothesis related with the body size structure of a population or community.

Species diversity of Spiders (Araneae) in Mimbilisan Protected Landscape, Misamis Oriental, Philippines

“…Considering the fact that male spiders reach maturity faster than females, Romero & Vasconsellos-Neto (2005) observed that female spiders are more frequently observed during adult and sub-adult stages while male spiders are frequent during the juvenile stage. High number of collected adults were observed since female spiders oviposit throughout the entire year (Nieto-Castañeda et al, 2012). Female spiders typically ders.…”

Population dynamics and phenology of two congeneric and sympatric lynx spidersPeucetia rubrolineataKeyserling, 1877 andPeucetia flavaKeyserling, 1877 (Oxyopidae)

“…The phenology of an organism is understood as the temporal variations in the life cycle of the individual (Menzel 2002;Romero and Vasconcellos-Neto 2003), and serves as an important aspect to understanding the population dynamics of a species (Wolda 1988). In spiders, the term phenology has been applied commonly to the study of variations in the age structure of populations (Romero and Vasconcellos-Neto 2003;Villanueva-Bonilla and Vasconcellos-Neto 2016) and to describe the life cycle of individuals (Nieto-Castañeda et al 2012). Tretzel (1954) and Paquin and Dupérré (2001) argue that spiders may have four phenological patterns based on the reproductive period of the population as determined by the peak abundance of adult males.…”

Las arañas de los oasis de la región meridional de la península de Baja California, México

“…Otro aspecto que resalta de las arañas de este género es que poseen ciclos de vida muy peculiares, ya que presentan un solapamiento muy marcado en tallas corporales de diferentes estadios, resultado quizá de las diferentes tasas de crecimiento y el continuo reclutamiento de estos organismos, producto de ovoposición de las hembras durante todo el año. Estos patrones no han sido registrados para otras especies de arañas en las que han sido estudiados sus ciclos de vida (Nieto-Castañeda, Salgado-Ugarte y Jiménez, 2012).…”