Anatomy lecture 2

Question 1

Define Ontogeny

Answer 1

Ontogeny refers to the embryonic development of an organism as well as any developmental changes that occur after birth or hatching

Question 2

Define Von Baer’s Law

Answer 2

1) Features that develop EARLIEST in ontogeny are the oldest phylogenetically. 2) Features that develop later in ontogeny are of more recent phylogenetic development 3) Features common to all members of a major taxonomic group develop earlier in ontogeny than do special features that distinguish subdivisions of that group

Question 3

Define Teleology

Answer 3

The idea that characteristics develop because they are need. For example Birds needed to fly so they developed wings

Question 4

Describe the synthetic theory of evolution and list its 3 components

Answer 4

components: Organic evolution 2) genetic diversity 3) Theory of natural selection

Question 5

Define natural selection and list its two co-authors

Answer 5

Developed by Charles Darwin and Alfred Wallace
-Components: Genetic variability exists in sexually reproducing populations. Some members of the population may be better “fit” for a given environment than others. These individuals have better chances of survival and having fertile offsprings. The genotypes of these individuals will become more frequent in a population over many years. If the environment does not change, than the population may achieve genetic equilibrium, and evolution may take place very slowly or not at all.

Question 6

Describe the theory of acquired characteristics and list its author

Answer 6

Developed by Jean Lamarck
Components: During its lifetime an organism may develop anatomic changes in response to specific pressures it encounters. These acquired characteristics may then be passed on to its offsprings

Question 7

Define Analogy and Homology

Answer 7

Analogy: Similarity in function in structures in two or more diff species. Although the function is similar, the anatomy and the embryological development is DIFFERENT. Example: Wing of bird and wing of insect. Function same which is fly. But their anatomy and embryological development is different.

Homology: Structural similarity uniquely evolved (due to inheritance from a common ancestor or developed from a common embryonic anlage).
-Anatomy and development are similar, but function does NOT have to be similar. (so function can be same or cannot be same)
For example; Fin of dolphin and forearm of lizards, they superficially seem to be very different but they develop the same way physically and anatomically. but the function is different.

Question 8

Define Parallelism and Convergence

Answer 8

Parallelism: Independent development of similar characteristics in lineages that inherit from a common ancestor, a potential for such development BUT do not directly inherit the similar characteristics

Convergence: independent development of similar characters in two or more lineages. Even though they receive from the common ancestor, night the adaptions involved nor characteristics that channel the development of those adaptions. (Process whereby organism to closely related (not monophyletic), independently involve similar traits as a result of having to adapt to similar environments

Question 9

Shark and dolph. Are they convergence or parallelism?

Answer 9

Convergence. They are not from common ancestor but have similar function due to environment.

Question 10

Kangaroo and rabbit, convergence or parallelism?

Answer 10

Parallelism. They are both from the same ancestor wh o has a tail and hide legs. however rabbit and kangaroo both have large hind legs and large busy tail so they did not directly inherit the similar characteristics

Question 11

Define Peadomorphosis, Paedogenesis, Neoteny

Answer 11

Paedomorphosis is when the larval form does not metamorphosis, so the larval form becomes the adult form and develops gonalds and becomes more sexually mature.
Paedeogensis is the act of developing gonalds.
Neoteny: adult forms retain one or more larval characteristics.

Question 12

➢ Identify the geological period during which vertebrates first appeared and state how many years ago this was

Answer 12

Cambrian period, 570millions years ago

Question 13

➢ List characteristics of the hypothetical common ancestor of echinoderms and chordates

Answer 13

o	Sessile or semi-sessile
o	Deuterostomous
o	Coelomate
o	Bilateral symmetry
o	Ciliated larval form
o	Lophophorates
o	Ciliary feeders

Question 14

Define Clade

Answer 14

o Clade: a monophyletic group made up of an ancestor and all of its descendants

Question 15

Define Cladistics

Answer 15

o Cladistics: is an approach to biological classification in which organisms are categorized based on shared derived characteristics that can be traced to a group’s most recent common ancestor and are not present in more distant ancestors.

Question 16

Define Synapomorphies

Answer 16

o Synapomorphies: derived characters that are shared by several lineages

Question 17

Define Paraphyletic group

Answer 17

o Paraphyletic group: A group being discussed that includes a common ancestor and some but not all of its descendants

Question 18

Define Polyphyletic group

Answer 18

o Polyphyletic group: A group being discussed that includes descendants of a common ancestor but not he common ancestor.

Question 19

Define Cladogram

Answer 19

o Cladogram: a diagram that shows a sequential hypothetical evolutionary branching pattern of a group of clades.