comparative anatomy exam 1

comparative anatomy

Study of structure of organisms, with an emphasis on similarities caused by evolutionary relatedness

Anatomy

The study of the structure of organisms and their parts

Morphology

The form of an organism, often used as a synonym for anatomy

Evolution

Genetic change in a pop over time, often used to reference change in structure and function of an organism

Natural selection

Differential survival of different genetic types within a population, theory that describes a mechanism which causes evolutionary change

How natural selection works: Theory of Natural selection

1. Variation- all populations vary naturally

2. Overpopulation- all populations produce more offspring than can survive

3. Competition- resources are limited so competition between species

4. Differential reproductive success- variation allows some individuals to survive and reproduce better than others

5. Heritability - favorablehh traits are passed down from generation to generation

Variation

all populations vary naturally

Overpopulation

all populations produce more offspring than can survive

competition

resources are limited so competition between species

Differential reproductive success

variation allows some individuals to survive and reproduce better than others

Heritability

favorable traits are passed down from generation to generation

Fitness

The ability of an organism to get its genes into the next generation

Categories of evidence for natural selection

1. Direct observation

2. Homology

3. Fossil record

Homology

Similarities in anatomy or other genetic traits of a diffrent species due to shared ancestors

Analogy

Similarities if anatomy or other genetic traits of different species due to similar selection pressures rather than common ancestry (convergent evolution)

Pentadactyl

Term which refers to organisms which have five digits on each arm or leg, specifically referring to tetrapods and their immediate ancestors

Tetrapod

monophyletic group which includes all land vertebrates- amphibians, reptiles, crocodilians, turtles, birds and mammals

4 Homology Examples

1. Homologous structures

2. Serial Homology

3. Vestigial organs

4. Embryology

Serial Homology

Type of Homology in which successive body segments are based on a single plan, like annelids, arthropods, and chordates

Vestigial organs

Body part which no longer serves a function for which it originally evolved

Nicitating membrane

Inner third eyelid of some reptiles, birds, and mammals. Humans have a vestigial third eyelid

Atavism

Structure which has disappear over evolutionary time, but later reappears

Embryology

Division of biology which focuses on the study of embryological development

Fossil

any preserved trace of a long dead organism

Transitional fossil: Archaopteryx lithographica

An extinct bird which shows an evolutionary transition between ancestral dinosaurs and modern bird

Parsimony

The idea that the least complex explanation of those possible is most likely to be correct

Terms that describe relationships between structures

1. Homology

2. Analogy

3. Homoplasy

Homology

Similarities in anatomy or other genetic traits of different species due to shared ancestry

Analogy

Convergent evolution, similarities in anatomy or other genetic traits due to similar selection pressures rather than common ancestry

Homoplasy

Similarities in anatomy or other genetic traits of diffrent species not sure to common ancestry, or similar selection pressures, perhaps due to mimicry, crypsus or random chance

Mimicry

A close, non cryptic resemblance between two or more organisms which gives, one, both, or all an advantage or benefit in their relationship with predators or prey

phylogeny

Evolutionary history of a Taxon or group of taxa

Phylogram (cladogram)

A visual representation of a classification based upon evolutionary relationship

Dendrogram

A branching diagram which illustrates the relationship between taxa, if it is evolutionary history it will still be a phylogram or cladogram

Clade

Taxonomic grouping which contains a common ancestor and all of its descendants (monophyletic)

Paraphyletic

Refers to Taxon which contains an ancestral organisms and some but not all of its descendants

Ex: class reptilia

Monophyletic

Refers to taxa which includes a single common ancestor and all of its descendants (properly constructed clade)

Polyphyletic

Refers to Taxon which does not include the common ancestor of all organism included with it

Sister taxa

Two taxa who split from a common ancestor, on a dendrogram it will be the two branches that emerge from a node

Branch

Line on a dendrogram representing one of two taxa which emerge from the split which occurs at a node

Node

Point on a dendrogram where two taxa separate resulting in two branches

Root

Structures common ancestor

Derived

Relatively new in an evolutionary sense

Primitive

Relatively old in an evolutionary sense

Symplesiomorphic

Refers to structures or traits which are shared by two taxa and relatively primitive

Synapomorphic

Refers to structures which are shared and relatively derived

Carolus Linnaeus

Swedish botanist who devised the system of classification and nomenclature we use today

Kingdom

level of classification between domain and phylum

Phylum

Level of classification between kingdom and class

Class

Level of classification between phylum and order

Order

Level of classification between class and family

Family

Level of classification between order and genus

Genus

Level of classification between family and species

Species

Group of similar organisms which can reproduce successfully within the group but not with organisms outside the group, lowest level of classification

Taxon

Any scientifically named group of an organism

Fossils

Any preserved trace of a previously living organism

Trace fossils

A fossil which is a remnant of a formerly living thing, but dose not include a part of the organism itself

coprolite

Fossilized fecal matter

Sedimentary rock

Rock which is formed by the build up of layers of sediment at the bottom of large bodies of water, where fossils are usually found

Ingenious rock

Rock which is formed from volcanic lava

Radiometric dating

Technique which uses the known half lives of radioactive isotopes to determine the age of rocks and fossils by comparing the amount of the isotope present to the amount of its product

Stratigraphy

Study of rock layers and which fossils occurred in them

Geological time scale

System which divides the history of the earth based on the relative age of rocks in the earths crust and what fossils are found in each layer

Know geological time scale in order

Echinodermata

Phylum if bilateral animals which includes ,sea stars, brittle stars, sea cucumbers, and their relatives. It is related to chordates

Chordata

Phylum which includes animals with a notochord, pharyngeal slits, endostyle, dorsal hallow nerve cord, and a post anal tail. Phylum is divided into three subphylum’s, Urochordata, cephalochordata and vertebrata

Protochordate

An informal, paraphyletic grouping which includes hemichordates, urochordates, and cephalochordates

Hemichordata

Phylum of animals which includes acorn worms, are considered close relatives of chordates because they have:

Pharyngeal slits, and a dorsal nerve cord but lack a notochord and post anal tail

Filter feeders who live in sediment of marine habitats

Acorn worm

Common name for members in phylum hemichordata

Urochordata

Subphylum of phylum chordata that includes tunicates

Tunicates

Animal which is a member of subphylum urochordata

They are bottom dwelling, filter feeding organisms found in marine habitats.

They develop from a tadpole larva which have all the characteristics of chordates but undergo metamorphosis into adults who are sessile filter feeders which pump water through a mucus covered basket.

Sea squirt

Common name for tunicates in class Ascidacea

Ascidacea

Class within subphylum Urochordata which includes the most common tunicates called sea squirts

Tunic

The tough outer body covering of an adult tunicate

Cephalochordata

Subphylum of phylum chordata that includes lancelets (amphioxous)

Amphioxus

Informal common name for lancdlets in the subphylum cephalochordata.

Pikaia gracilens

Extinct fossil member of the subphylum Cephalochordata. It is one of the earliest known chordates. It was discovered in the Burgess Shale of Canada

Vertebrata

Subphylum of phylum Chordata that includes all animals with a bony or cartilaginous endoskeleton. Sometimes referred to as craniata

Know the 5 chordate characteristics

1. Notochord

2. Dorsal hallow nerve cord

3. Post anal tail

4. Pharyngeal slits

5. Endostyle

Notochord

A cartilaginous rod which runs the length of the dorsal side of the body of members of phylum Chordata.

The notochord is used for attachment of muscles which allow chordates to use their post anal tail for swimming

Nerve cord

A large nerve which runs the length of the dorsal side of the body of members of phylum Chordata. The chord is hollow, and in vertebrates, the anterior end everts during embryological development to become the brain

Endostyle

A longitudinal ciliated groove on the central wall of the pharynx which produces mucus to gather food particles.

It is found in urochordates, cephalochordates, and some vertebrate larvae, and is homologous to the thyroid gland in more derived vertebrates

Thyroid gland

An endocrine gland found in most adult vertebrates which is a major control gland for metabolism. It is homologous to the endostyle

Pharyngeal slits

Openings found in the pharynx of members of phylum Chordata. The openings allow filter feeding in some members of the group, and are used as gill slits in some more derived members

Post anal tail

A muscular tail that extends past the anal opening, found in members of phylum Chordata. Makes chordates strong swimmers compared to most invertebrates.

Myomere

One of the segmented muscle blocks found in the vertebrate body.

Padeomorphis

The retention of larval characteristics in sexually mature animals

Know the three hypothesis for the evolutionary origin of chordates

1. inverted arthropods

2. Echinoderm derivation

3. Echinoderm-cephalochordate derivation

Inverted arthropod hypothesis

Idea that Arthropods simply flipped over and dorsal became ventral

Echinoderm Derivation

Idea that the Larva of echinoderms who have similar characteristics to chordates, underwent padeomorphosis and reproduced

Echinoderm- cephalochordate derivation

Idea that the Common ancestors of chordates split from echinoderms and hemichordates and at some point flipped over

Bilateria

clade of animals within kingdom Animalia which includes all animals with bilateral symmetry. Includes all animals except sponges, cnidarians, placozoans, and ctenophores

Bilateral symmetry

A type of symmetry in which a single plane (the sagital plane) can be used to divide an animal into mirror image left and right sides. Bilateral animals also have an anterior and posterior end and a dorsal and ventral surface

Coelomate

Any animal which has a coleum, a body cavity which contains and allows movement of internal organs, especially the digestive tract

Deuterostome

Any clade of animals within the bilateria which have a pattern of embryological development in which the first opening in the blastula becomes the anus and the second opening becomes the mouth.

this group includes chordates, hemichordates, and echinoderms

Protostome

Any clade of animals within the Bilateria which have a pattern of embryological development where the first opening in the blastula becomes the mouth and the second becomes the anus.

This group included the arthropods, mollusks, nematodes, annelids, tardigrades, and many other vertebrates

Diplerula

Hypothetical larva like common ancestor of all dueterostomes

Vertebra

Any of a series of bones which make up the spinal column of vertebrates

Craniata

Alternate name for subphylum Vertebrata

Cranium

The set of bones which supports and surrounds the brain of vertebrates.