14,24,25) While this supports the previous hypothesis that retrotransposons in the genome provide genetic materials to generate novel genes, (85) it has also led to the novel concept that at least in some cases the LTR retrotransposon-derived genes contributed to mammalian evolution, such as the emergence of viviparity
Remarkably, however, once these species evolve viviparity
, the process is mostly irreversible and they remain restricted to such cold climates.
Reproduction in the lizard Mabuya hethi (Scincidae): a commentary on viviparity
in new world Mabuya.
With the sole exception of Tomeurus gracilis Eigenmann, which is characterized by oviparous egg retention, internal fertilization and viviparity
are found in all species of poeciliids (Rosen 1964).
and intragonadal cannibalism in the diminutive asterinid sea stars Patiriella vivipara and P.
Their topics include the evolution and taxonomy of snakes, oogenesis and early embryogenesis, viviparity
and placentation, hormones and reproduction in free-ranging snakes, environmental and neuroendocrine control of reproduction in snakes, the sexual segment of the kidney, pheromones in snakes, offspring size variation, paternity patterns, and parental care in snakes.
Some immunological and endocrinological problems raised by evolution of viviparity
The evolution of viviparity
in reptiles: an ecological analysis.
While the phenomenon has not been given the attention it deserves there are a number of cases that have recently appeared in the literature including bilateral shift to asymmetry in the animal kingdom, the shell shape in freshwater snails, viviparity
in reptiles, sex determination in turtles, leaf form in buttercups, and ant attracting extra-floral nectar secretion in Acacia trees (Palmer, A.
A cost of viviparity
and parental care in scorpions: reduced sprint speed and behavioural compensation.
Reproductive biology and phylogeny of fishes (agnathans and bony fishes); phylogeny, reproductive system, viviparity
The yolkless egg and the evolution of eutherian viviparity
Key words: polychaeta, Syllidae, Coiba, Pacific, Panama, viviparity
Beyond the relatively simple question of when a crop will flower, there are a number of problems in reproductive development, including pollen incompatibility in both self and cross species situations, apomixis, parthenocarpic fruit set, embryo abortion, viviparity
, dormancy, and quality of seed.
A cost of viviparity
and parental tare in scorpions: Reduced sprint speed and behavioural compensation.