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Comparative Anatomy Concepts & Premises Note Set 1 Chapters 1 & 2.

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Presentation on theme: "Comparative Anatomy Concepts & Premises Note Set 1 Chapters 1 & 2."— Presentation transcript:

1 Comparative Anatomy Concepts & Premises Note Set 1 Chapters 1 & 2

2 Phylogeny Historical relationship between organisms or lineages Historical relationship between organisms or lineages Ancestry shown by phylogenetic tree Ancestry shown by phylogenetic tree Phylogenetic Systematics- shows relationships from past to present Phylogenetic Systematics- shows relationships from past to present Shows evolutionary relationships Shows evolutionary relationships Figure 2.1

3 Major Vertebrate Groups Figure 2.2

4 Cladistics Method for studying phylogeny Method for studying phylogeny Shows ancestry of derived features Shows ancestry of derived features Advanced structures are derived, synapomorphic Advanced structures are derived, synapomorphic Primitive structures are not derived, ancestral, symplesiomorphic Primitive structures are not derived, ancestral, symplesiomorphic Figure 2.3

5 Convergence- organism response to similar environment Convergence- organism response to similar environment Similar structures yet distantly related organisms Similar structures yet distantly related organisms Ex: limbs of fishes and marine mammals Ex: limbs of fishes and marine mammals Parallelism- structure similarities in closely related organisms Parallelism- structure similarities in closely related organisms Similar morphology due to parallel evolution Similar morphology due to parallel evolution Ex: Dog and gray wolf skull Ex: Dog and gray wolf skull Figure 2.4

6 Paedomorphosis Paedomorphosis- Ontogenetic changes where larval features of ancestor becomes morphological features of descendant Paedomorphosis- Ontogenetic changes where larval features of ancestor becomes morphological features of descendant Juvenile character stage of ancestor is retained Juvenile character stage of ancestor is retained Figure (Left) larval state salamander with external, feathery gills; (Center) adult salamander that lost gills; (Right) adult axolotl salamander retains juvenile external gills.

7 Paedomorphosis (cont.) Figure 2.6: Natural selection pressures on the wolf may have lead to the formation of a new species, the domestic dog. The prehistoric adult dog skull (center) can be compared to the adult wolf skull (left) and particularly the juvenile wolf skull (right).

8 Neoteny- delayed rate of somatic development Neoteny- delayed rate of somatic development Progenesis- precocious sexual maturation in morphological juvenile Progenesis- precocious sexual maturation in morphological juvenile Behavioral Paedomorphology- juvenile behavioral stage retained Behavioral Paedomorphology- juvenile behavioral stage retained Ex: wolf pup and domestic dog Ex: wolf pup and domestic dog Heterochrony- change in rates of character development during phylogeny Heterochrony- change in rates of character development during phylogeny Paedomorphosis (cont.)

9 Generalized- structure with broad function Generalized- structure with broad function Ex: human hand Ex: human hand Specialized- structure with restricted function Specialized- structure with restricted function Ex: single digit hand Ex: single digit hand Modification- change from previous state, may be preadaptive Modification- change from previous state, may be preadaptive Preadaptation- current trait that will be useful in future Preadaptation- current trait that will be useful in future Ex: binocular vision and thumb Ex: binocular vision and thumb

10 Amniotes- higher vertebrates with amniotic sac Amniotes- higher vertebrates with amniotic sac Ex: reptiles, birds, mammals Ex: reptiles, birds, mammals Anamniotes- lower vertebrates without amniotic sac Anamniotes- lower vertebrates without amniotic sac Ex: fish, amphibians Ex: fish, amphibians Amnion- membrane sac that surrounds embryo Amnion- membrane sac that surrounds embryo Cleidoic egg- amniotic egg with shell Cleidoic egg- amniotic egg with shell Higher vs. Lower Vertebrates

11 Serial homology- serial repetition of body parts in single organism Serial homology- serial repetition of body parts in single organism Ex: Somites Ex: Somites Figure 2.7: Somite formation in 4 week old embryo.

12 Vestigial- phylogenetic remnant that was better developed in ancestor. (e.g., human appendix, fruit fly wings, python leg spurs) Figure 2.8: Ball python spurs. Vestigial

13 Rudimentary Phylogenetic sense- structure is fully exploited by a descendant Phylogenetic sense- structure is fully exploited by a descendant Ex: rudimentary lagena in fish (sac of semicircular canals) develops into organ of Corti in mammals Ex: rudimentary lagena in fish (sac of semicircular canals) develops into organ of Corti in mammals Ontogenetic sense- structure is underdeveloped or not fully developed from embryo to adult Ontogenetic sense- structure is underdeveloped or not fully developed from embryo to adult Ex: Muellerian tract in females develops into reproductive tract; yet in males, duct is rudimentary Ex: Muellerian tract in females develops into reproductive tract; yet in males, duct is rudimentary Ex: Woffian duct in males develops into sperm duct; yet in females, duct is rudimentary Ex: Woffian duct in males develops into sperm duct; yet in females, duct is rudimentary

14 Adaptive Radiation- diversification of species into different lines through adaptation to new ecological niches Adaptive Radiation- diversification of species into different lines through adaptation to new ecological niches Figure 2.9: Branching evolution; increased diversity.

15 Sea Squirt Free Swimming Larva Larval stage of sea squirt resembles vertebrate tadpole Larval stage of sea squirt resembles vertebrate tadpole Developed notochord and dorsal nerve cord Developed notochord and dorsal nerve cord Rudimentary brain and sense organs Rudimentary brain and sense organs Figure 2.10: Larval form of sea squirt. Figure 2.11: Lamprey larval structures.

16 Sea Squirt Sessile Adult Once larva attaches, notochord and nervous system disappear Once larva attaches, notochord and nervous system disappear Resembles invertebrate Resembles invertebrate Figure 2.13: Adult sea squirt structures (see book figure 3.4). Figure 2.12: Adult sea squirt.

17 Literature Cited Figure Figure Figure 2.3- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, Figure Figure Figure 2.6- Morey, Darcy F. The Early Evolution of the Domestic Dog. American Scientist, Vol. 82, No. 4, p342. Figure Figure Figure Figure ml Figure Figure Figure


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