Animal Biology Eam 2

Mendel

Scientist who used peas to discover and explain how genes function (Recessive or dominant)

Heritable features

character (genes)

variation of a character

trait (alleles)

allele

alternative of the same gene (D or

gene

protein responsible for specific factor (eg. flower color)

law of segregation

alleles for heritable character segregate during gamete formation (meiosis)

Law of independent assortment

separation of homologous chromosomes during meiosis (different traits can be inherited independently or mixed)

Test cross

how you would test if a parent that is showing the dominant phenotype is homologous or not

Incomplete dominance

hybrids will happen when the generation shows a mixture between two or more phenotypes

codominance

2 dominant alleles affect the phenotype in separate, distinguishable ways

evolution

process by which species accumulate differences from their ancestor as they adapt to different environments over time

adaption

inherited characteristics that enhance organism survival and reproduction in specific environment

Natural selection

process which certain individuals with certain traits tend to survive and reproduce at a higher rate because they have those traits.

Homology

similar structures in non-similar organisms ; evidence for evolution. proof that there was a common ancestor.

analogous

NOT from a common ancestor ; trait that arose through independent adaptation to function in similar environments

conditions for hardy weinberg

1. random mating

2. no mutations

3. no natural selection

4. extremely large population

5. no gene flow

Genetic drift

process in which chance events cause allele frequencies to fluctuate unpredictably from one generation to the next (reduces genetic variations within population due to random allele loss)

Founder effect

random colonization events.

individuals becoming isolated from a larger population

bottleneck effect

drastic reduction in population size because of a sudden environmental change

gene flow

movement of alleles among populations through the mixing from fertile individuals (inc genetic variation in one population but decreases between populations)

Directional Selection

Only favoring one extreme of the phenotypic range

Disruptive Selection

Favoring both extremes of the phenotypic range

Stabilizing selection

favoring intermediate variants

Intrasexual selection

direct competition among individuals of one sex

intersexual selection

individuals of one sex choosy in selecting a mate

biological species

• can interbreed in nature

• produce viable, fertile, offspring
  do not produce viable offspring with members of other such groups

prezygotic barriers (1)

Habit

Prezygotic barriers (2)

mechanical, gametic: NO successful

postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown : Individuals or their offspring are not fertile

Allopatric speciation

populations are geographically isolated, gene flow is interrupted (habitat changs/ colonization)

Sympatric speciation

speciation occurs in populations that live in the same geographic area (habitat differentiation / sexual selection)

phylogeny

evolutionary history of a species or group of related species based on shared characteristics

Binomial

two-part scientific name incl genus and species-specific name

taxonomic group hierarchy

domain, kingdom, phylum, class, order, family, genus, species

evolutionary lineage

sequence of ancestral organisms leading to a descendant taxon

sister taxa

groups that share a CA, not shared by any other group

clade

group of species that includes an ancestral species and ALL of it descendants

shared ancestral character

character originating in an ancestor of the taxon (older)

shared derived character

evolutionary novelty unique to a particular clade (newer)

embryonic development in animals

1. Cleavage - succession of cell division without growth between

2. blastula forms. often in the form a hollow ball of cells

3. blastula undergoes gastrulation and forms a gastrula with different embryonic tissues

radial symmetry

body parts on a single axis. sessile or planktonic animals

bilateral symmetry

arranged around two axis (head-tail and dorsal-ventral). Only one imaginary slice will divide the animal into a mirror image (h to t). Active animals with a central nervous system

diploblastic animals

cnidarians ; only have ectoderm and endoderm

triploblastic animals

have ectoderm, endoderm, and a mesoderm layer between them (gives rise to muscles and organs)

coelom

body cavity surrounded only by mesoderm

hemocoel

body cavity surrounded by endoderm and mesoderm

protostome development

• spiral cleavage (planes of division diagonal to vertical axis of embryo) and determinate cleavage (rigidly determines developmental fate of each embryonic cell)

• splitting of solid masses of mesoderm forms coelom

• blastopore becomes mouth

dueterostome development

• radial cleavage (parallel or perpendicular planes of division) and indeterminate cleavage (cell produced by early cleavage is able to form a complete embryo)

• mesoderm buds from the wall to form the coelom

• blastopore becomes anus

porifera

sessile, filter feeders, lacking true tissues

how sponges eat

spongocoel - water filled cavity

pores - water with food will enter here to spongocoel

Choanocytes - flagellated cells will trap food particles in mucus

phagocytosis - food particles engulfed

amoebocyte - food is transported here and the nutrients are transported to other cells of the sponge

Cnidaria

radially symmetrical, diploblastic animals with gastrovascular cavity

polyp ; body plan of cnidaria

• gastrovascular cavity for digestion

• attach to substratum and move slowly

• uses tentacles to capture food

medusa ; body plan of cnidaria

• gastrovascular cavity for digestion

• moves freely in water

• tentacles to catch food

medusozoans

all cnidarians that produce a medusa (they may also have a polyp life stage)

(jellies and hydrozoans)

Anthozoans

only polyp life stages (sea anemones and corals)

Lophotrochozoa (clade)

classified on molecular data and named due to morphological features

Patyhelminthes (clade)

flatworms with bilateral symmetry and a central nervous system ; no body cavity ; no circulatory organs

planarians (free-living flatworms)

have light sensitive eyespots

reproduce asexually by fission

hermaphrodites (copulating mates cross-fertilize each other during sexual reproduction)

Trematodes

flatworm species ; parasitic ; complex life cycles with alternating sexual (human) and asexual stages (snail)

Mollusca phylum

(snails, slugs, oysters, clams) most are marine; soft bodies of many are surrounded by calcium carbonate shell

anatomy of molluscs

Visceral mass - contains the main organs

Mantle - fold of tissue that secretes the shell

Foot - used for movement

Radula - scrapes up food

clades of molluscs

1. polyplacophora (chitons)

2. gastropoda (snails and slugs)

3. Bivalvia (clams, oysters, and other bivalves)

4. Cephalopoda (squids, octopuses, cuttlefish, and chambered)

Annelids

segmented worms - clades: errantia and sedentaria

errantia

marine ; paddle or ridge-like parapodia on each body segment that is used for locomotion and gills

sedentarians

less mobile and often are burrowing animals

ecdysozoans

animals with a cuticle and tough external coat. Largest - nematodes and arthropods

arthropod main features

segmented body, exoskeleton, jointed appendages