Organismal Biology: Climate, Biomes, Ecological Niches, and Meiosis

Comprehensive vocabulary flashcards generated from key lecture material covering climate drivers, biomes, Texas ecotypes, ecological niches, genetic variations, and meiosis.

Weather

The short-term condition of precipitation, temperature, and wind occurring at a specific moment in a given area.

Climate

The long-term trend and pattern of precipitation, temperature, and wind measured over extended periods for a regional area or the entire globe.

Greenhouse Effect

The atmospheric process in which gases such as $\text{CO}_2$, $\text{H}_2\text{O}$, and $\text{CH}_4$ absorb low-energy infrared radiation (heat) emitted from Earth's surface and trap it in the atmosphere, warming the planet.

Geographic Range Shift

A climate-driven movement of a species' spatial distribution, such as the nine-banded armadillo expanding northward from South Texas to Nebraska and Illinois due to warmer winter temperatures.

Phenological Shift

A change in the seasonal timing of life-cycle events in organisms, such as Ashe juniper ("mountain cedar") beginning its winter pollen release earlier and extending its duration due to warmer autumn and winter temperatures.

Solar Irradiance and Angle of Incidence

The distribution pattern of sunlight intensity per unit area across Earth, where solar radiation is concentrated overhead at the equator and spread across a lower angle near the poles.

Earth's Axial Tilt

The $23.5^\boxdot$ tilt of Earth relative to its orbital plane, which causes global seasons by changing the directness of solar angle in each hemisphere throughout the year.

Atmospheric Chemistry (Climate Factor)

The proportion of heat-trapping greenhouse gases ($\text{CO}_2$, $\text{H}_2\text{O}$, $\text{CH}_4$) relative to non-absorbing gases ($\text{N}_2$, $\text{O}_2$) in the atmosphere, which determines total energy retention.

Balcones Canyonlands Ecotype

A Central Texas ecological region characterized by rocky limestone hills, thin soils, dense juniper and live oak, and localized endemic species.

Blackland Prairie Ecotype

A Central Texas ecological region characterized by deep clay soils and open tallgrass grassland, historical areas of which have been largely converted to agricultural land.

Savannah Ecotype (Central Texas)

A Central Texas ecological region featuring sandy acidic soils with scattered oak trees over a grassy understory.

San Marcos River Ecotype

An aquatic Central Texas ecological region fed by constant $70\,^\circ\text{F}$ spring water, providing stable conditions for unique endemic species found nowhere else.

Karst Cave Ecotype

A subterranean Central Texas ecological region consisting of dark, stable, low-nutrient limestone cave environments supporting specialized subterranean organisms.

Bald Cypress Ecotype

A Central Texas aquatic-adjacent ecological region restricted strictly along permanently wet river margins.

Ecology

The scientific study of interactions between organisms and their environment, derived from the Greek root oikos meaning "home."

Abiotic Factors

The non-living physical and chemical components of an environment, such as sunlight, temperature, and precipitation, that set physiological limits for species.

Biotic Factors

The living components of an ecosystem, including interactions such as predation, competition, herbivory, and disease, that constrain species distribution and abundance.

Fundamental Niche

The complete range of environmental conditions (such as temperature and moisture) under which a species can physiologically survive and reproduce without biotic constraints.

Realized Niche

The restricted range of environmental conditions an organism actually occupies in nature as a result of biotic constraints like competition and herbivory.

Niche Model

A statistical model that predicts species geographical distribution by fitting occurrence data to environmental parameters such as temperature and precipitation.

Alleles

Variant DNA sequences of the same gene formed by mutation, which give rise to distinct phenotypic traits among individuals of a species.

Chromosome

A eukaryotic nuclear structure consisting of a single long double helix of DNA wound around associated proteins that carries linear genes coding for traits.

Homologous Chromosomes

A pair of chromosomes of the same type in diploid cells that possess identical gene loci in identical positions, but may carry different maternal and paternal alleles.

Sister Chromatids

The two identical, duplicate strands of a replicated chromosome joined together at a central centromere prior to cell division.

Ploidy

The total number of complete sets of chromosomes present within a cell, categorized as haploid ($n$) for one set or diploid ($2n$) for two sets.

Meiosis

A specialized cell division process involving two rounds of division that reduces chromosome numbers from diploid ($2n$) to haploid ($n$) to produce genetically varied gametes.

Anaphase I

The specific stage of Meiosis I during which homologous chromosome pairs separate and move toward opposite poles of the spindle apparatus, transitioning the cell from diploid to haploid.

Independent Assortment

The random orientation and segregation of different maternal and paternal homologous chromosome pairs during Meiosis I, producing $2^n$ possible combinations of chromosomes in gametes.

Chiasma

An X-shaped physical connection site between non-sister chromatids of homologous chromosomes where genetic material is swapped during crossing over.

Pathogen and Parasite Hypothesis

The evolutionary hypothesis proposing that coevolving pathogens and parasites drive the maintenance of sexual reproduction over asexual reproduction by selecting for genetically diverse offspring.