1. Reproduction Mating - physiological - morphological - behavioral/social events Tied to life history (annual and life cycle) Interesting variations - asexual reproduction - sperm storage - viviparity - parental care - sex determination - heterochrony Pough et al., 2001

2. Sexual vs. Asexual Reproduction Sexual male gamete + female gamete = zygote haploid sperm haploid egg diploid offspring Meiosis - recombination leads to genetically variable gametes

3. Sexual vs. Asexual Reproduction Asexual ~ hybrid origin ~ female populations ~ clonal reproduction Parthenogenesis - 30 species of squamate - many Cnemidophorus (1/3) - pseudocopulation - deleterious mutations Komodo Dragon female ZW male ZZ Hybridogenesis - e.g., Rana; female genome unchanged Gynogenesis - e.g., Ambystoma; no genes from male Pough et al., 2001

4. Sexual vs. Asexual Reproduction Figure 7-1 Pough et al. 2001 No recombination

5. 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.

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

7. female male

8. 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

10. Parthenogenesis When females reproduce without the involvement of males or sperm Offspring “clones” of their mother Occurs in 7 lizard clades & 2 snake clades

11. Reproduction (neuronal, hormonal, behavioral) Figure 7-3 Pough et al. 2001 light, heat, moisture space, food, habitat pop. density, hierarchy gonadotropin releasing hormone estrogen testosterone

12. Reproduction (patterns) Figure 7-4 Pough et al. 2001 Timing - behavior - physiology Temperate vs. Tropical ? Sperm Storage? Most Common?

13. Reproduction (fertilization) Amphibians External = ancestral Internal: Caecilians - phallodeum (almost all) Salamanders - spermatophore (most) Anurans - ‘tail’ or cloacal apposition (quite rare) Reptiles Internal Sphenodontids - cloacal apposition Turtles and Crocs - penis Squamates - hemipenes

14. Reproduction (gametes) Figure 7-5 Pough et al. 2001 Reptiles (amniotic egg) - shell - membranes - H2O, protection Amphibians (anamniotic) Egg - ovary to oviduct - yolk (from liver)

15. Reproduction (nutrition and sex determination) oviparous viviparous (more when talk about parental care) Lecithotrophic - rely on yolk Placentotrophic - additional nutrients from mother GSD- Genotypic Sex Determination heterogamety, variable in herps TSD- Temp.-dependent Sex Determination many reptiles not known to occur in amphibs

16. Pough et al. 2001

17. TSD

18. - During middle third or half of development - Gene activity temp. dependent? - alter testosterone (in yolk from mother) - Females: aromatase produced converts testosterone to estradiol (estrogen) stimulates creation of ovaries and more estrogen secondary sexual characteristics etc. -Males: 5alpha-reductase produced converts testosterone to dihydrotestosterone stimulates creation of testes and more androgens secondary sexual characteristics etc.

19. Amphibian Life Cycles and Reproductive Modes Common: egg --> larva --> adult Direct Development skip the larval stage (e.g., Eleutherodactylus) Paedomorphosis skip the adult stage Notophthalmus add a juvenile eft stage Notophthalmus viridescens (Eastern Newt)

20. Amphibian Life Cycles and Reproductive Modes Caecilians - mostly oviparous --> larvae or direct Salamanders - oviparous (pond, stream, nonaquatic) - direct in Plethodontids Anurans - oviparous ancestrally - eggs variable, correlated with habitat (clumps, strings, foam, etc.) - trend to move on to land small pools seed husks bromeliads, etc. - multiple evol. of direct development

21. Rana berlandieri, Big Bend N.P., Texas

22. Pough et al. 2001

23. Salamanders

24. Pough et al. 2001 Anurans

25. Amphibian Larval Development and Metamorphosis Caecilians - basically small adults with gills - lose eyes, gain tentacles Salamanders - small adults with gills, larval dentition - always carnivorous Anurans - variable - days to years as tadpole - metamorphosis is dramatic (suspension feeding to carnivore) adult gut and stomach develop jaws, teeth, tongue eyelids, lungs, ossification Dendrobates auratus

26. Stebbins and Cohen, 1995 Anuran metamorphosis

27. Metamorphosis Density dependent variation – when growth conditions are poor, larvae should metamorphose near the minimum size; when conditions are good, larvae should metamorphose near the maximum size Plasticity in larval growth paedomorphosis

28. Reptilian Egg and Embryonic Development Oviparity or viviparity - no larval stage Shell - calcium carbonate layer, fibrous inner layer - thin to thick (vary the outer mineral layer) - thinnest in viviparous species ~ thin if take water from environment Gas exchange, water, temperature Birds, crocs, tuataras, some turtles - ~no water uptake Squamates and some turtles - lots of water uptake

29. Heterochrony - common evolutionary tool rate offset onset e.g., Ambystoma A. tigrinum A. mexicanum Figure 7-11 Pough et al. 2001 (obligate vs. facultative)

30. Ambystoma mexicanum (paedomorphic) Ambystoma tigrinum (larval) Ambystoma tigrinum (adult) Pough et al. 2001

31. paedomorphosis

32. Parental Care costs vs. benefits to parents Amphibs caecilians- egg attendance (all) salamanders- egg attendance (20%) anurans- diverse (10%) - egg attendance, transport Rheobatrachus vitellinus - egg and tadpole development (outside oviduct) - tadpole guarding, transport - tadpole feeding Pipa pipa

33. Pough et al. 2001 Male Parental Care in Eleutherodactylus coqui

34. Parental Care Reptiles turtles - rare, ineffective? crocs- all, vocalizations squamates- some - nest defense - egg attendance (several snakes) - egg brooding (e.g., Pythons) - hatchling attendance (a few viviparous species, e.g., some Crotalus) Python regius

35. Viviparity (Parental Care) = retention of embryos in oviduct until development complete Found in - some caecilians (~20%) - a few frogs - a few salamanders (some Salamandrids) - some squamates (~20%); no turtles, crocs - reduced shell thickness - increased gas exchange - maintenance of hormone levels - lecithotrophy - placentotrophy - matrotrophy - assoc. with cold (in squamates) - trade-offs Fig. 17-13 Stebbins and Cohen, 1995

36. Life History Reproductive Effort (RCM, relative clutch mass) - current vs. future - current vs. survival Energy per Progeny 1 vs. 50,000 eggs/clutch Figure 7-20 Pough et al. 2001 parental care and viviparity => few large egg size optimized? constrained? Trade-offs?

37. Uta Rana cascadae Xenosaurus

38. Mating Systems and Sexual Selection Sexual Dimorphism African reedfrog, Hyperolius argus veiled chameleon

39. Mating Systems and Sexual Selection Sexual Selection - secondary sexual characteristics -Directional selection that acts on genetically variable phenotypic traits that affect the reproductive success of the individuals of a particular sex Coloration Size Crests -Usually in the male b/c females are the limiting resource

40. Mating Systems and Sexual Selection Sexual Selection Darwin 1871 as cited in Pough et al. 2001 male

41. Mating Systems and Sexual Selection Sexual Selection Two components: 1. Male – male competition for access to females 2. Female choice (of which male to mate with) Pough et al. 2001

42. Males more affected by sexual selection than females Females – spend energy on egg production ability Males – a whole lot of little cheap sperm Magnitude of sperm production favors fertilization of eggs from many females Males do not need to find quality mates, rather quantity mates

43. Mating Systems and Sexual Selection Mating Systems Most herps polygynous - Individual male reproductive success variable - Some males mate with more than one female - Many males don’t mate at all Females Choose By?

44. Why do females prefer certain phenotypic traits? 1)Direct Benefit: Certain male characters (nuptial gifts of food or defensive compounds, care provided to offspring) 2)Good genes: Male characters are "indicators" of "good genes", i.e., 3)Sensory bias or sensory drive: some aspect of the sensory world biases females

45. Natural Selection vs. Sexual Selection Sexual Selection and Natural Selection may actually oppose each other –Increased color/ behavior that attracts predation –Increased cost of maintaining a territory –Heavy weaponry

46. Mating Systems and Sexual Selection Mating Systems Behavioral tactics used by males depends on the spatial and temporal distribution of females: 1. Many clumped briefly = explosive scramble 2. Few dispersed = males go searching 3. Intermediate = many options… - Mate guarding Grade into each other Intraspecific variation - Signalling to attract - dispersed - lekking - Defend territories - food resources - nesting sites

47. Mating Systems and Sexual Selection Mating Systems Explosive Mating Aggregations - Temporary ponds Spea, Scaphiopus, ~Rana -Flood the world with sperm -some ambystomatid salamanders and frogs Pough et al. 2001 -Spatial aggregation some Thamnophis, Natrix (spring at den) Males outnumber females (e.g., 10-1) male-male competition Sexual Interference including

48. Rana sylvatica Bufo bufo, Scaphiopus

49. Sperm Competition Multiple paternity –the red-eyed tree frog (Agalychnis callidryas), the Australian frog (Crinia georgiana), and the common frog (Rana temporaria). Genetically superior sperm more likely to survive (better to mate with several males) Chiromantis xeramplina – African gray treefrog

50. High numbers of male garter snakes die soon after emerging from hibernation because they are attacked by crows. She- males at the center of a mating ball, however, are less exposed to predators – also remain warmer… Thamnophis sirtalis parietalis – males swamp the few females that emerge…

51. Male Female Explosive 1980 1981

52. Mating Systems and Sexual Selection Mating Systems Mate Searching - some salamanders - common in reptiles - turtles and tortoises - snakes tend to be solitary follow pheromones - populations may vary density fewer, widely dispersed = more search time and more waiting - widely foraging lizards Thamnophis sirtalis

53. Mating Systems and Sexual Selection Mating Systems Mate Searching - Crotalus viridis Overwinter in communal dens Disperse in spring and forage widely Males search for females in midsummer Most males don’t find a female Long term strategy

54. Mating Systems and Sexual Selection Mating Systems Mate Guarding: If searching for mate is costly, then it may be worthwhile to invest energy in guarding her from other males - amplexus in anurans and salamanders salamander - male may physically carry away female - male with enlarged teeth used to deter other male Atelopus (Bufonidae) -male may amplex weeks/months before breeding season - costs to female and male

55. Mating Systems and Sexual Selection Mating Systems Mate Guarding Gopherus agassizii - Male searches for female - Stays with her many days - Wards off other males use of gular Territorial lizards - male will guard female - forfeit other females photos by Roger A. Repp Tiliqua rogusa - multi-year pair bonds Some Snakes - often wrestling contests - ‘topping’ Crotalus atrox

56. Mating Systems and Sexual Selection Mating Systems Leks = aggregations of males that gather in sites, defend small territories, and display for females Females choose males based on their traits -color, size, vigor, display structures Triturus cristatus Marine iguana

57. Chorus = anuran males calling from particular perches

58. Mating Systems and Sexual Selection Mating Systems Resource Defense Resources attractive to females - oviposition sites - feeding areas Male mating success depends more on resource quality than on the characteristics of the male per se Not common in salamanders, but: Cryptobranchids with external fertilization - defend territories with nesting sites Red-backed salamanders (Plethodon cinereus) - female judges territory quality based on male feces (termites better than ants) Male size and vigor may be correlated

59. Mating Systems and Sexual Selection Mating Systems Resource Defense Resources attractive to females - oviposition sites - feeding areas Rana clamitans (green frogs) Rana catesbeiana (bullfrog) Territories guarded for ~2 months (during breeding season) appropriate oviposition sites (water temperature) Territorial Lizards Male with large quality territory likely to encompass many female territories Pough et al. 2001

60. Mating Systems and Sexual Selection Male Reproductive Success Some males mate many times Many males don’t mate at all Variance in reproductive success leads to strong sexual selection and sexual dimorphism - Search time - Competition - Attractiveness - Handling time - Parental care

61. Some males mate many times Many males don’t mate at all

62. Mating Systems and Sexual Selection Male Persistence and Allocation of Resources Stamina Salamander lesson: e.g. Amount of time male anuran spends in chorus positively correlated with mating success Sacrifice energy reserves and foraging opportunities Explosive aggregations (~Ambystoma) males deposit many, many spermatophores most not picked up by a female Courtship (~Salamandridae, Plethodontidae) males court extensively, deposit few spermatophores – female picks up

63. Sacrifice energy reserves and foraging opportunities

64. Mating Systems and Sexual Selection Male Competitive Ability - explosive breeding aggregations - mate searching - mate guarding Also important for territorial species (indirectly) ~ Larger body size Pough et al. 2001

65. Mating Systems and Sexual Selection Male Competitive Ability/ Sexual Dimorphism - Frog fangs - Frog wrestling - Frog trunk muscles - Newt tail fins - Lizard biting - Snake wrestling Pough et al. 2001 Male-male assessment - size - color - repeat encounters

66. Pough et al. 2001 Male Males wrestling Female Amplexus

67. Mating Systems and Sexual Selection Alternative Mating Tactics - Sneaking/Satellite - Female Mimicry - Sexual Interference Pough et al. 2001 Uta stansburiana orange super male blue mate guarder yellow sneaker

68. Alternative Mating Tactics Small males more likely to behave as satellites Small satellites density and satellites

69. Mating Systems and Sexual Selection Sperm Competition - amount - vigor - longevity Male vs. Female size - sexual selection - clutch size - ecological roles (diet) Uta stansburiana Atelopus