Thresholds to sexual maturity—either age or size—are critical life history parameters. Usually investigated in short-lived organisms, these thresholds and interactions among age, size, and growth are poorly known for long-lived species. A 34-year study of captive green turtles (Chelonia mydas) that followed individuals from hatching to beyond maturity provided an opportunity to evaluate these p...

Heritability, environmentaland genetic correlations between body weight at hatch (BW0), eight (BW8) and twelve (BW12) weeksof age, body weight at sexual maturity (BWM), age at sexual maturity (AFE),the weight of the first egg laid by the hen (EWM), the mean egg weight from 28 to 32 wks (EW28-32) and egg numbers (ENs) were estimated by the restricted maximum likelihood method under an animal mod...

Free-ranging mantled howling monkey (Alouatta palliata Gray) females experienced a regular estrus cycle averaging 16.3 days, demonstrated sexual skin changes, and participated in multiple matings before becoming pregnant. Gestation averaged 186 days. The average interval between births was 22.5 months. Sexual maturity occurred at approximately 36 and 42 months for females and males, respectivel...

asymptomatic malaria (asm) has been implicated in the development of hemolytic crisis in infected sickle cell anemia (sca) patients worldwide. this study surveyed steady state sca nigerian patients for asm to investigate the influence of malaria prevention behaviors and age on parasitaemia and multiplicity of infection (moi). a total of 78 steady sca patients aged 5 – 27 years on routine care a...

The differential allocation hypothesis predicts that reproductive investment will be influenced by mate attractiveness, given a cost to reproduction and a tradeoff between current and future reproduction. We tested the differential allocation hypothesis in the swordtail fish Xiphophorus multilineatus, where males have genetically influenced (patroclinous inheritance) alternative mating tactics ...

BACKGROUND Few human studies have evaluated the impact of childhood exposure to organochlorine pesticides (OCP) on pubertal development. OBJECTIVE We evaluated associations of serum OCP concentrations [hexachlorobenzene (HCB), β-hexachlorocyclohexane (βHCH), and p,p-dichlorodiphenyldichloroethylene (p,p´-DDE)] with age at attainment of sexual maturity among boys. METHODS From 2003 through 2...

The present study was undertaken to examine the effect of recombinant chicken leptin administered to fed ad libitum and feed-restricted immature chickens of a layer strain on ovarian development and the timing of sexual maturity. In the first experiment 11-week-old pullets (77 days of age) fed ad libitum were injected daily with leptin at four dose levels (4, 16, 64 and 256 microg/kg body weigh...

Social conditions experienced prior to sexual maturity influence reproduction later in life in many animals. In simultaneous hermaphrodites variation in mating group size influences reproductive investment. As the mating group size increases, reproductive resources devoted to the female function decrease in favor of the male function. Prior to sexual maturity many hermaphrodites have a protandr...

Observations of the external morphology of wild-caught and captive male brown long-eared bats (Plecotus auritus) revealed a marked seasonal pattern of spermatogenesis, similar to that established by histological examination of other temperate-zone vespertilionids, with a peak in testes size in August and a lag between testicular growth and epididymal distension. This was followed by complete ce...