Comprehensive Biology 130: Ecology, Evolution, Diversity, and Statistics

Practice vocabulary flashcards for Biology 130 covering animal diversity, plant structure and life cycles, population demography, community dynamics and succession, taxonomy and phylogenetics, adaptation mechanisms, and statistical analysis.

Protostomes

A major developmental lineage of animals (including Annelida, Nematoda, Arthropoda, and Mollusca) characterized by spiral cleavage at the 8-cell stage and the development of the blastopore into the mouth.

Deuterostomes

A developmental lineage of animals (including Chordata and Echinodermata) characterized by radial cleavage at the 8-cell stage and the development of the blastopore into the anus.

Ecdysozoa

A protostome animal group including Arthropoda and Nematoda whose members possess an exoskeleton and grow by molting or shedding it through ecdysis.

Lophotrochozoa

A protostome animal clade including Annelida and Mollusca that share early embryonic developmental patterns and similar larval forms despite having divergent adult body forms.

Bilateral Symmetry

A body organization in which only a single plane divides the organism into two identical left and right halves.

Hydrostatic Skeleton

A structural skeletal support system that uses internal fluid pressure to maintain body form and assist movement in soft-bodied animals.

Alternation of Generations

A plant life cycle that alternates between a multicellular haploid ($1n$) gametophyte generation producing gametes and a multicellular diploid ($2n$) sporophyte generation producing spores.

Stomata

Microscopic pores in the leaf epidermis flanked by specialized guard cells that regulate gas exchange ($\text{CO}_2$ uptake) and water loss via transpiration.

Bryophytes

Nonvascular land plants (mosses, liverworts, hornworts) lacking roots, true leaves, and vascular tissues, featuring a dominant haploid gametophyte generation and swimming flagellated sperm requiring water for fertilization.

Pteridophytes

Seedless vascular plants (ferns, horsetails, whisk ferns, club mosses) with xylem and phloem, featuring a dominant diploid sporophyte generation, dispersal via haploid spores, and flagellated sperm dependent on water.

Gymnosperms

Vascular seed plants (conifers, cycads, ginkgoes) that bear naked seeds not enclosed within fruit, using pollen grains to transport sperm without relying on water for fertilization.

Angiosperms

Vascular flowering plants that produce flowers and enclose their seeds within fruits, featuring double fertilization and highly reduced male and female gametophytes.

Double Fertilization

An angiosperm reproductive process where one sperm cell fertilizes an egg to produce a diploid ($2n$) embryo, and a second sperm fuses with two polar nuclei to form triploid ($3n$) endosperm.

Pistil

The central female reproductive organ of a flower, composed of the stigma, style, and ovary containing one to many ovules.

Meristem

Specific plant tissues consisting of undifferentiated cells that divide, elongate, and differentiate to initiate primary and secondary growth.

Vascular Cambium

A lateral meristem cylinder running beneath the bark that produces secondary xylem toward the stem interior and secondary phloem toward the stem exterior, driving radial diameter growth.

Pollination Syndrome

The suite of floral traits (color, scent, shape, nectar, and pollen rewards) that have evolved to attract specific pollinator groups based on their sensory biases and feeding morphologies.

Population

A group of individuals of the same species living within a given geographic area that have the potential to interbreed.

Demography

The ecological subdiscipline concerned with the tracking and statistical study of the fates of individuals in a population over time, including births, deaths, immigration, and emigration.

Carrying Capacity ($K$)

The critical population density at which the birth rate equals the death rate, causing population growth to level off under density-dependent resource limitation.

Density-Independent Factors

Environmental influences—such as droughts, severe freezes, floods, and fires—that impact population size regardless of how crowded individuals are, without actively regulating the population around carrying capacity.

Interspecific Competition

An ecological interaction ($--$ or $-0$) where individuals of different species exploit the same limiting resource, reducing the survival, growth, or reproduction of one or both species.

Mutualism

A symbiotic biotic interaction ($+ +$) in which both interacting organisms derive a fitness benefit, such as food, gamete dispersal, nutrients, or protection.

Commensalism

A biotic interaction ($+ 0$) in which one organism benefits while the other is largely unaffected without significant fitness cost or gain.

Ecological Community

An assemblage of interacting populations of different species coexisting within a defined geographic area.

Keystone Species

A species that plays an outsized role relative to its own abundance in determining the structural patterns and functional integrity of its ecological community.

Limiting Resource

An essential environmental factor (such as water, soil nutrients, or sunlight) that restricts the growth and productivity of an organism or community when in shortest supply.

Disturbance

A discrete physical or biological event in time that abruptly alters community structure, removes biomass, and changes resource availability, creating opportunities for new colonizers.

Primary Succession

The directional establishment and development of an ecological community on a newly formed or completely sterilized substrate devoid of pre-existing vegetation, seeds, or developed soil.

Secondary Succession

The directional recovery and re-establishment of an ecological community following a disturbance that leaves the soil intact and retains biological legacies like seeds, rootstocks, or survivors.

Non-equilibrium Dynamics

The modern ecological paradigm that communities exist in continuous, unpredictable states of recovery from multiple recurring disturbances, rather than progressing toward a permanent climax equilibrium.

Type III Survivorship Curve

A survivorship pattern characterized by extremely high mortality among young or small individuals, followed by relatively high survival rates once adulthood is reached, forming an inverse-J distribution.

Taxonomy

The biological field devoted to the identification, scientific naming, and hierarchical classification of organisms into nested categories based on shared characteristics.

Clade

A monophyletic group on a phylogenetic tree consisting of a common ancestor and all of its descendant lineages, living and extinct.

Homologous Characters

Structures or traits present in different organisms that are similar because they were inherited directly from a shared common ancestor that possessed that trait.

Analogous Characters

Superficially similar traits in distinct lineages that evolved independently due to convergent evolution under similar selective pressures, rather than being inherited from a common ancestor with the trait.

Principle of Parsimony

The phylogenetic criterion stating that the tree hypothesis requiring the fewest evolutionary steps or character-state transitions is preferred as the most probable explanation.

Adaptation (Noun)

An inherited phenotypic trait favored by natural selection because it enhances an organism's survival or reproductive success in its current environment.

Hyoid Bone

The skeletal structure supporting the tongue; in woodpeckers, it extends from the nostrils, splits between the eyes, and wraps entirely around the skull to protect the brain and project the tongue outward.

Vestigial Structures

Anatomical traits that were adaptive in an organism's ancestors but have lost their original function through evolutionary change, remaining only as non-functional evolutionary by-products.

Pseudogenes

Vestigial gene sequences within an organism's genome that have acquired disabling mutations causing the complete loss of their original protein-coding ability.

Reciprocal Transplant Experiment

An experimental technique testing whether a trait is adaptive by measuring the relative fitness of organisms with contrasting phenotypes in both their native home environment and an alternative away environment.

Vernal Pools

Geographically isolated, ephemeral wetlands underlain by clay that hold water seasonally between November and May, excluding fish predators and serving as critical breeding sites for amphibians.

CAM Photosynthesis

A specialized photosynthetic pathway in succulent xerophytes where stomata open only at night to absorb and chemically store $\text{CO}_2$, preventing daytime transpiration before completing carbon fixation in sunlight.

Scientific Hypothesis

A testable, falsifiable statement predicting how a specific aspect of the natural world functions, usually derived from prior observations.

Independent Variable

The variable in an experiment or observational study that is manipulated, controlled, or hypothesized to act as the cause of a change.

Dependent Variable

The measured response variable in an observational study or experiment that is affected by changes in the independent variable.

Interquartile Range (IQR)

A measure of statistical dispersion representing the central $50\%$ of ordered data points bounded between the $25\text{th}$ and $75\text{th}$ percentiles around the median.

Right-Skewed Distribution

An asymmetric data distribution with an elongated tail stretching toward higher positive values, causing the mean to be greater than the median.

Sampling Error

The statistical difference between a true population parameter and the value estimated from a measured sample of that population.

Null Hypothesis ($H_0$)

The default hypothesis in statistical testing positing that there is no difference between compared group means ($\Delta = 0$) or no association between variables ($\text{slope} = 0$).

p-value

The probability of observing a test result as extreme as, or more extreme than, the sample data under the assumption that the null hypothesis is true.

t-test

A statistical hypothesis test used to compare the means of two distinct groups when the independent variable is categorical and the dependent variable is continuous or a count.

Coefficient of Determination ($R^2$)

A linear regression metric ranging from $0$ to $1$ that indicates the proportion of variance in the dependent variable explained by the independent variable.