Modern Amphibian Diversity

Transcription

1 Modern Amphibian Diversity 6,604 species (about the same number of mammals) 5,839 of these are frogs; 584 salamanders; 181 caecilians all continents except Antarctica mostly tropical caecilians Anura 88% Caudata 9% Gymnophiona 3%

2 Modern Amphibian Diversity Gymnophiona Limbs absent, body elongate Eyes covered with skin or bone Left lung reduced Tentacle present Male copulatory organ (phallodeum) always present Size range: 70 mm to 1.5 m 6 families: Caeciliidae Ichthyophiidae Rhinatrematidae Scolecomorphidae Typhlonectidae Uraeotyphlidae

3 Modern Amphibian Diversity Gymnophiona

4 Modern Amphibian Diversity Tentacle - protrusible olfactory organ in front of eyes. Develops during metamorphosis. Gymnophiona

5 Modern Amphibian Diversity Gymnophiona Phallodeum - protrusible male copulatory organ (from Duellman & Trueb)

6 Modern Amphibian Diversity Gymnophiona Reproduction - 75% of species are viviparous and use both lecithotrophy and matrotrophy.

7 Modern Amphibian Diversity A new form of nutrition has recently been discovered in a species from Africa. The young eat the outer layer of the mother s skin. This skin feeding is called dermatophagous. Gymnophiona

8 Modern Amphibian Diversity Gymnophiona

9 Modern Amphibian Diversity Gymnophiona - Relationships

10 6,604 species (about the same number of mammals) 5,839 of these are frogs; 584 salamanders; 181 caecilians all continents except Antarctica mostly tropical Frogs Anura 88% Caudata 9% Gymnophiona 3%

11 Frogs are highly specialized amphibians - specialized for what? Astragulus and calcaneum are fused forming a 4th main leg segment Fusion of radius & ulna into single element (same for tibia & fibula) Shortened vertebral column (9 or fewer pre-sacral vertebrae) Hindlimb longer than forelimb Vocal sacs well developed in males of most species No tail (in adults) Tongue is large and protrusible Size range: 90 mm to 30 cm Aquatic larvae, when present, lack true teeth, have keratinous beaks, and have fold of skin covering gills 38 families

12 Fusion of leg elements in anurans

13 Protrusible tongue Prey capture

14 Protrusible tongue

15 Vocal sacs in males

16 Keratinized beak in tadpoles

17

18 Relationships Leiopelomatidae Ascaphus & Leiopelma All other frogs

19 Relationships Ascaphus

20 Relationships Ascaphus & Leiopelma Pipidae Rhinophrynidae All other frogs

21 Relationships Pipidae Pipa pipa Surinam toad Xenopus laevis African clawed frog

22 Relationships Rhinophrynidae Rhinophrynis dorsalis Mexican burrowing toad

23 Relationships Characters important in diagnosing groups: pectoral girdle type number of pre-sacral vertebrae number & placement of spiracle in tadpoles

24 Relationships

25 Relationships Bombinatoridae

26 Relationships Alytidae

27 Relationships Bufonidae - over 500 species

28 Relationships Ranidae - over 800 species

29 Modern Amphibian Diversity- Anura Relationships Leptodactylidae - over 1400 species

30 Relationships Rhacaphoridae - gliding frogs

31 Modern Amphibian Diversity- Anura Relationships Dendrobatidae - poison arrow frogs

32 Relationships Hylidae - tree frogs-- over 800 species

33 Modern Amphibian Diversity- Anura Relationships Microhylidae

34 Reproduction Fertilization is external except in a few species in 4 genera Therefore most are oviparous with aquatic eggs and larvae Some are oviparous, with direct development of terrestrial eggs Some are viviparous (mostly lecithotrophy) Many species exhibit bizarre forms of parental care

35 Reproduction, Amplexus Inguinal Inguinal is thought to be the ancestral character state Axillary

36 Reproduction, Amplexus (males shaded) inguinal axilliary cephalic glued independent straddle

37 Reproduction, Internal Fertilization Family Species Mechanism Parity Nutrition Internal Fertilization & Viviparity Ascaphidae A. trueii Via intromittent organ ( tail ) Oviparous Lecitotrophy Bufonidae Nectophrynoides N. tornieri Cloacal apposition Viviparous Lecitotrophy N. viviparous Cloacal apposition Viviparous Lecitotrophy N. occidentalis Cloacal apposition Viviparous Lecitotrophy then matrotrophy Mertensophryne Via intromittent organ (modified cloaca) Viviparous? Leptodactylidae Eleutherodactylus E. coqui Cloacal apposition Oviparous Lecitotrophy E. jasperi Cloacal apposition Viviparous Lecitotrophy

38 Reproduction, Internal Fertilization Internal Fertilization & Viviparity

39 Reproduction Family Species Mechanism Development Alytidae Alytes obstetricians Males carry eggs on back and carries tadpoles to aquatic habitat indirect Extrauterine Viviparity and Other Parental Care Dendrobatidae several Both sexes carry tadpoles to aquatic habitat both Pipidae Pipa Eggs embedded in female dorsum both Hylidae Fritziana Flectonotus Females carry eggs on back, openly or in pouches indirect Hemiphractus Gastrotheca Cryptobatrachus Amphignathodon Stefania Females carry eggs on back, openly or in pouches. Placenta- like capillary network sometimes develop direct Leptodactylidae Cyclorhamphus stejnegeri Females carry tadpoles to aquatic habitat indirect Myobatrachidae Rheobatrachus Silus R. vitellinus Females "eat" eggs or tadpoles and they develop in stomach and emerge as froglets Both Assa Males carry tadpoles in paired inguinal pouches, emerge as froglets indirect

40 Reproduction Family Species Mechanism Development Extrauterine Viviparity and Other Parental Care Rhinodermatidae Rhinoderma rufum Males "eat" tadpoles and they develop in vocal pouches and emerge as tadpoles indirect R. darwinii Males "eat" tadpoles and they develop in buccal cavities and emerge as froglets indirect Sooglossidae Sooglossus sechellensis Non-feeding tadpoles wriggle onto back of males indirect Hemisotidae Hemisus Females attend eggs and carry tadpoles to aquatic habitat indirect Hyperolidae Hyperolius obstetricians Leptopelis brevirostris Females may brood direct developing eggs in mouth direct Ranidae Rana microdisca Males carry tadpoles to aquatic habitats indirect

41 Reproduction Extrauterine Viviparity and Other Parental Care Gastric brooding frog, Rheobatrachus silus

42 Modern Amphibian Diversity Anuran Reproduction/ Parental Care Strawberry Poison Frog, Dendrobates pumilio, male carrying tadpole on back Poison Frog, Dendrobates granuliferus, female carrying tadpole on back

43 Modern Amphibian Diversity Anuran Reproduction/ Parental Care The Surinam Toad, Pipa pipa, female with eggs (left) and tadpoles embedded on back

44 Modern Amphibian Diversity Anuran Reproduction/ Parental Care Pouched Frog, Gastrotheca ovifera, female with froglets emerging from pouches on back

45 Modern Amphibian Diversity Anuran Reproduction/ Parental Care Darwin Frog, Rhinoderma darwini, male and froglet. Eggs are eaten by the male and they develop in throat pouches and emerge as froglets.

46 Reproduction Neoteny Why is there no neoteny in anurans? Some species are completely aquatic and neoteny (in salamanders, anyway) involves the lack of a switch from aquatic to terrestrial There are vast differences in the ecology of adult and larval anurans: Tadpoles are almost exclusively plant eaters, adults are not. A plant diet requires a large gut (why?) which leaves no room for ova, oviducts, etc.