An experiment in which a lupin grain supplement was fed to ewes (n = 11) over days 2-13 of the oestrous cycle carried out. A group 12 used as control and not supplement. Plasma concentrations LH GH (20 min intervals) FSH, insulin prolactin (hourly were determined plasma samples collected every 20 24 h on day 11 cycle. The changes related increases ovulation rate. Ovulation rate increased (2.5 +/- 0.2 versus 1.9 for lupin-supplemented groups, respectively; P 0.073) that received supplement,...

A defining feature of tetrapod evolutionary origins is the transition from fish fins to limbs. major change during this appearance autopod (hands, feet), which comprises two distinct regions, wrist/ankle and digits. When first appeared in Late Devonian fossil tetrapods, it was incomplete: digits evolved before full complement bones. Early wrists/ankles, including those with a bones, also show sharp pattern discontinuity between proximal elements distal elements. This suggests presence...

1. Understanding individual and population responses to climate change is emerging as an important challenge. Because many phenotypic traits are sensitive environmental conditions, directional could significantly alter trait distribution within populations may generate evolutionary response. 2. In species with environment-dependent sex determination, lead skewed ratios at hatching or birth. However, there virtually no empirical data on the putative link between climatic parameters from...

Locomotor strategies in terrestrial tetrapods have evolved from the utilisation of sinusoidal contractions axial musculature, evident ancestral fish species, to reliance on powerful and complex limb muscles provide propulsive force. Within tetrapods, a hindlimb-dominant locomotor strategy predominates, its evolution is considered critical for success tetrapod transition onto land. Here, we determine developmental mechanisms pelvic fin muscle formation living species at points within...

Abstract The positive relationship between nutrition and ovulation rate was investigated in sheep infused intravenously with glucose. Ovulation increased (2·0±0·0 vs 2·4 ± 0·3) when ewes were given an infusion of glucose (60–65 mm/h) for five days the late luteal phase oestrous cycle. effect obtained without any significant change LH secretion. concentration FSH glucose-infused lower during (luteal phase) but higher early follicular phase. These data suggest that occurred gonadotrophin...

Two primary dichotomies within vertebrate life histories involve reproductive mode (oviparity versus viviparity) and sex determination (genotypic environmental determination). Although reptiles show multiple evolutionary transitions in both parameters, the co–occurrence of viviparity environmental–dependent have heretofore been regarded as incompatible. Our studies on viviparous lizard Niveoscincus ocellatus that extent basking by a female influences her offspring. Critically, our data...

Side biases in behavior, reflecting lateral specializations of the brain, are widespread amongst vertebrates. We studied laterality Australian lungfish <i>(Neoceratodus forsteri)</i> to gain insight into evolution complementary predator avoidance (right hemisphere) and foraging behavior (left hemisphere). Because <i>N. forsteri</i> is closest extant ancestor first land-dwelling vertebrates, knowledge this species should provide a missing link transition from fish...

How the hand and digits originated from fish fins during Devonian fin-to-limb transition remains unsolved. Controversy in this conundrum stems scarcity of ontogenetic data extant lobe-finned fishes. We report patterning an autopod-like domain by hoxa13 fin development Australian lungfish, most closely related relative tetrapods. Differences tetrapod limbs include absence digit-specific expansion hoxd13 hand2 distal limitation alx4 pax9, which potentially evolved through enhanced response to...

Gambusia holbrooki is a small, aggressive fish introduced into Australia in 1925 to control mosquitoes. It has been suggested that this species may also prey on tadpoles and be contributing factor the decline of some Australian frog populations. We examined influence tadpole body size (10 mm. 15 mm 20 mm). predator ratio (1 : 1, 1 :2 :4) nutritional status level predation by G. Limnodynasfas peronii. Unfed attacked all three classes without any significant preference but did so more...

Three peptides containing the melanotropin‐core amino‐acid sequence, YXMXHFRWG, were isolated from pituitary glands of a modern representative most primitive vertebrates, sea lamprey, Petromyzon marinus. MSH‐A, nonadecapeptide (NPELYQMNHFRWGQPPTHF), is free at both ends. MSH‐B, an eicosapeptide (VQES ADG YRMQHFRWGQPLP), N ‐terminus and amidated C ‐terminus. They differ strikingly gnathostome MSHs in structure. The third peptide, with apparent molecular weight 15 kDa, was tentatively...

Haploid genomes greater than 25,000 Mb are rare, within the animals only lungfish and some of salamanders crustaceans known to have this large. There is very little data on structure size. It known, however, that for animal up 3,000 Mb, there in general a good correlation between genome size percent composed repetitive sequence component highly dynamic. In study, we sampled Australian using three mini-genomic libraries found with sequence, results converged an estimate 40% being recognizable...

The positive relationship between nutritional state and ovulation rate in sheep may involve the action of specific nutrients on gonadotrophin release. LH FSH secretion is controlled part by hypothalamic GnRH, which turn influenced central adrenergic serotonergic neuronal systems. In this experiment branched chain amino acids (BCAAs) leucine, isoleucine valine were examined for effects secretion. A mixture three was infused into ewes 5 days immediately before luteolysis, a time when occur....

The development and differentiation of the gonads embryonic alligators incubated at 30 °C (100% female producing) 33 male was investigated histologically. stage gonad into an ovary or a testis occurred essentially same time both temperatures. This contrasts with overall embryos which slower lower temperature. A few days prior to differentiation, grew more quickly than they did °C. However, once differentiated presumptive testis, reduced in volume so that hatching testes were smaller ovaries....

The fish-tetrapod transition was one of the major events in vertebrate evolution and enabled by many morphological changes. Although transformation paired fish fins into tetrapod limbs has been a topic study recent years, both from paleontological comparative developmental perspectives, interest focused almost exclusively on distal part appendage particular origin digits. Relatively little attention paid to pelvic girdle small unipartite structure large tripartite weight-bearing structure,...

Abstract The effects of capture and temperature stresses on plasma concentrations testosterone (T) progesterone (P) were examined in wild male tuatara ( Sphenodon punctatus ), the only living sphenodontid reptile. Free‐roaming Stephens Island, New Zealand, had low levels (0.3–0.5 ng/ml) T July (winter), high (15–17 January (summer). Levels November appeared intermediate (5 but measured with reference to standards prepared human rather than plasma. These seasonal variations are consistent...

Male jacky dragons, <i>Amphibolurus muricatus</i>, indicate territoriality to rivals during the mating season through use of stereotyped motor displays. The relationship between corticosterone (B) and testosterone (T) its effects on territorial display expression were investigated in captive lizards. Results demonstrated that production was most effectively predicted by elevated baseline T levels. This parallels heightened concentrations exhibited males field spring period....

The majority of research into the timing gonad differentiation (and sex determination) in reptiles has focused on oviparous species. This is largely because: (1) most are oviparous; (2) it easier to manipulate embryonic developmental conditions (e.g., temperature) eggs than oviductal embryos and (3) modes determination taxa were thought be more diverse since viviparity environmental (ESD)/temperature-dependent (TSD) considered incompatible. However, recent evidence suggests two may well...