BIOL 233 definitions

Phenotypic Population

Genetically similar (but not identical) organisms that live in the same place at the same time

Phenotype

Observable characteristics of an organism

Variance

How “spread out” the data is

Gene

A region of dna that contains the instructions for a protein/functional molecule

Allele

Variations of the same gene

Phenotypic plasticity

Expression of certain genes is altered in response to external environment (same genotype —> different phenotype)

Epigenetic changes

Alteration to structure of dna without alteration to nucleotide sequence

Biological Evolution

Change in the relative proportion of alleles (i.e. allele frequencies) in a population over multiple generations

Descent with modifications

In a population descendants become more different from ancestors with increased time

Fitness

Measure of reproductive success of a biological category (biological category : average chance of survival x # offspring = fitness value)

Adaptive

Correlated with increased fitness, a trait that is associated with increased fitness, the process of adaptive traits becoming more common in a population (adaptation requires evolution)

Natural selection

Consistent differences in fitness between/among biological categories

Fixed trait

No variation same in 100% of population

Niche

Everything an organism needs/the role an organism occupies/performs in its environment

Convergence/analogy

Independent evolution of the same phenotype in different lineages due to similarity of environment/niche

Acclimatization

Organism gets used to an environment

Directional selection

one “extreme” of the phenotype spectrum has highest fitness

• Can cause adaptation if acting on heritable traits, shifts mean

Disruptive selection

intermediate phenotypes have lower fitness than either extreme

• Intermediates have lowest fitness, makes extremes more common but usually doesn’t shift the mean

Stabilizing selection

intermediate phenotypes have higher fitness than either extreme

• Intermediates have highest fitness, may not shift mean but decreases variances

Artificial selection

Natural selection with humans choosing which individuals produce offspring, based on desired on desired traits —> exaggeration

Unnatural selection

Natural selection with humans removing certain phenotypes from the population

Sexual selection

Natural selection that arises from competition for mates that is stronger within one sex than the other

Isogamy

All gametes the same

Anisogamy

Different gametes

Inclusive fitness

Your alleles passed on, Direct fitness —> own offspring carry alleles, indirect fitness —> shared alleles passed down via offspring of relatives

Monomorphic populations

Males/females phenotypes ~ the same —> same level of investment in offspring between males + females

Operational sex ratio

Males vs. Females in a pop that are available to produce new offspring —> impacted by parental care —> while caring for one brood, less/not available to produce new offspring or if one sex provides more parental care = less available

Sexual dimorphism

Distinct male + female phenotypes

Intrasexual selection

Competition within 1 sex

Intersexual selection

Between two sexes

Honest signal

Observable to members of the group, can’t be faked

Genetic Drift

evolution due to luck/chance —> not correlated with fitness of phenotype

Gene flow

Movement of alleles from one gene pool to another —> requires successful interbreeding

Effect greater if populations are very distinct

Gene flow is frequent, acts to homogenize populations into one big population/gene pool

• acts to make populations more similar

Speciation

Splitting of ancestral population into 2 or more species

Biological species concept

Group of genetically similar organisms that is reproductively isolated from other groups

• does not work for asexual organisms or allopathic/ extinct organisms

Allopatric speciation

Geographic barriers to gene flow

Sympathies speciation

Not geographic separation, but restricted gene flow anyway

Niche partitioning

Organisms specializing in different niches within the same environment

• different resources/roles in animals usually reinforced by sexual selection + behaviour

Prezygotic barriers

Prevent zygote from being formed

Postzygotic barriers

After zygote has formed

Habitat isolation

Different species occupy/make in different habitats within some geographic location

Behavioural isolation

Different species have different courtship/mating behaviours

Temporal isolation

Different species mate at different times

Mechanical isolation

Parts of different species don’t match

Gametic isolation

Gametes of 2 species are incompatible

Hybrid inviability

Hybrids don’t survive to adulthood (most embryos inviable)

Hybrid sterility

Hybrids cannot reproduce or very rarely (back crosses)

Hybrid reinforcement barrier

Hybrids are less fit than either purebred species. The species continue to diverge until hybridization can no longer occur

Hybrid fusion barrier

Reproductive barriers weaken until the two species become one

Hybrid stability barrier

Fit hybrids continue to be reproduced

Phylogenetic Parsimony

Fewer steps = stronger tree

Taxo

Group of organisms with a formal name

Nodes

Point where lineage splits

• represents most recent common ancestor of the descendant lineage

Clade

A node (common ancestors) and all of its descendants. Aka a monophyletic group

• only valid taxon

Homology

Similarity among different taxa that is inherited from a shared ancestor with the same trait

Homoplasy

Similarity that is not inherited from a shared ancestor

• often due to convergence

Vestigial

Reduced trait

Paraphyletic

ancestor and some (but not all) of its descendants

Polyphyletic

Organisms descended from more than one ancestor (excluding nodes & lineages connecting them)

Linnean ranks

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

Format: Genus species —> if written than must be underlined

Sporangium

Spore producing structure

Antheridia

Produce sperm

Archegonia

Produce eggs

Xylem

Conducts water and dissolved nutrients upward form root

Phloem

Conducts sugars and metabolic products from leaves

Sporophylls

Produce sporangia, where spores are produced

Sori

Clusters of sporangia

Strobili

Cone-like structures

Pterophyta

Spores in sori underside of leaves

Lycophyta

Spores in strobili club like structures w/clusters of sporophylls

Saprobes

Absorbs dead matter

Hyphae

Long filaments made of cells, 1 cell thick but many cells long

Mycelium

Body of an individual fungus, mass of connected hyphae

Septate fungus

Cells are separated by septa, pores

Coencytic fungus

No septa between cells, no continuous multinucleate cell

Cytoplasmic streaming

Redistribution of nutrients

Segmentation

Division into repeating units

Metamerism

Groups of segment that becomes specialized

Coelom

Body cavity in addition “hollow” to digestive cavity —> only applies to triploblasts

Acoelomate

No coelom, solid mesoderm between body wall tight

Pseudocoelomate

Coelom enclosed by mesoderm on one side, but by gut on other

Coelomate

Fluid filled coelom completely surrounded by mesoderms

Radial symmetry

Organism parts are arranged around central point allows organism to move equally in all directions, advantageous for animals that are sessile or move slowly

Bilateral symmetry

Organisms body can be divided into two halves along single plane, allows for directional movement, typically forward movement advantageous for animals that actively move and have distinct front and back ends

Chemotaxis

Following chemical signals toward areas of higher concentration

Epithelial tissue

Protection, transport, secretion, and absorption of nutrients released by digestion of food

Connective tissue

Structural support

Muscle tissue

Movement

Nervous tissue

Communication coordination and control

Choanocytes

Trap, absorb and digest food particles

Amoeboid cells

• Move around within the sponge back

• Redistribute nutrition from choanocytes

• Seed + receiving chemical signals

• Make spicules

Cnidocytes

Nematocyst discharged into prey when triggered barbed, many contain neurotoxins

Peristalsis

Alternating contractions of circular & longitudinal muscles in waves, using setae to anchor if on land

Cranium

Protective structure surrounding the brain

Vertebrae

Repeating structures that replace the notochord & protect nerve cord

Cartilage or bone

Two major vertebrae connective tissues