1. Reproduction & life histories I.Reproductive cycles II.Modes of Fertilization III.Asexual reproduction IV.Evolution of parental care V.Parental care VI.Viviparity

2. I. Reproductive cycles A.Environmental stimuli  Moisture, temperature, food availability, amount of sunlight, stimulate GnRH –Amphibians = rain & temperature –Reptiles = temperature In temperate climates - Soil temperatures and insolation only high enough to allow rapid embryonic development in summer

3. B.Hypothalamus – Pituitary axis –GnRH Gonads  Annually  Biennially

4. Oogonia are self-renewing stem cells that persist for the life of the frog Can generate a new cohort of oocytes each year

5. Growth of oocytes in the frog. During the first 3 years of life, three cohorts of oocytes are produced. The drawings follow the growth of the first-generation oocytes.

6. Reptilian cycles Associated Dissociated Continuous

7. C. Breeding behavior Location & stimulation of potential mates, primarily associated with males. In most amphibians, males compete among themselves for mating opportunities – females do the choosing –Ova more costly than sperm, thus female output is limited by resource availability and time constraints – not mate availability Salamanders Anurans Reptiles

8. II.Fertilization modes of amphibians A.External B.Internal –Evolved independently several times –Only a few Anurans, 90% salamanders & all caecilians Salamanders: Spermatophore, females able to retain… –Mating separate from oviposition

9. III. Asexual Reproduction

10. A. Hybridogenesis  When females produced via hybridization between 2 closely related species produce only female offspring (all genetically identical to the mother)  This mode marks hybrids between two parental species (A,B) who are able to reproduce by backcrossing with one of the parents.  These hybrid normally contain two chromosome sets (AB, one from each parent species) in their body cells, but in the gonads the chromosome set of one parent is lost, so that only one set remains (A or B), with A in their gonads, hybrids can backcross with B and vice versa.

11. R. lessonae R. ribidunda R. esculenta RL, RLL, RRL

12. female male

13. B. Gynogenesis Egg development activated by a spermatozoon, but to which the male gamete contributes no genetic material Ambystoma laterale-jeffersonianum complex: females use sperm from a sympatric, diploid male to initiate the development of the eggs without incorporating the male genome

14. A.texanum (TT) laterale (LL) jeffersonianum (JJ) Triploid, unisexual females: LLJ LLT LJJ Hybridogenesis: LJ LT JT

15. C. Parthenogenesis Occurs in 7 lizard clades & 1 snake clade C. neomexicanus asexual species C. inornatus C. tigris

16. IV. Evolution of parental care Parental investment in offspring after the eggs have been deposited or young have been born –Amphibian: –Reptile: Mom vs. Dad

17. V. Ecology of Anuran Metamorphosis Dramatic morphological & physiological changes Density dependent variation when growth conditions are poor, Plasticity in larval growth

18. VI. Vivparity Viviparity – derived condition, specializations for embryonic development in uterus In reptiles - Associated w/ colder climates, female can regulate her body temp. behaviorally In reptiles - Associated only w/squamates In amphibians – Caecilians & a few Anurans

19. In viviparous amphibians, nutrition for embryos is