Biology Chapter on Cells and Evolution

A specific location on a chromosome where a gene resides.

A specific version or variant of a gene. Think of genes as books, and alleles as different editions of that book - similar content but with unique variations.

The complete genetic makeup of an individual, representing the specific combination of alleles an organism carries.

The observable physical and physiological characteristics resulting from an organism's genotype, influenced by environmental interactions.

When an individual carries two identical alleles at a specific genetic location. For example, having two identical 'blue eye' alleles.

When an individual carries two different alleles at a specific location. Like having one 'blue eye' allele and one 'brown eye' allele.

A mathematical model that describes the genetic equilibrium of a population under specific conditions: no mutation, random mating, large population size, no gene flow, and no natural selection. It uses allele and genotype frequencies to predict the genetic makeup of a population.

A type of natural selection where extreme phenotypes within a population are favored over intermediate phenotypes. This can lead to the divergence of a population into two or more distinct groups.

The random changes in allele frequencies within a population, often due to chance events. It is more influential in smaller populations, leading to the potential for allele fixation or loss.

The movement of genetic material (alleles) between different populations. It can prevent separate populations from becoming distinct species by homogenizing gene pools.

Heritable changes in DNA sequences, which are the ultimate source of genetic variation in a population. They can involve changes in single base pairs or larger rearrangements of DNA segments.

Mating between closely related individuals, which can lead to increased homozygosity (both alleles of a gene are the same) and potentially reduced fitness due to the expression of harmful recessive alleles.

A type of natural selection where individuals with certain traits are more successful at attracting mates and securing reproductive opportunities. It can lead to the evolution of extravagant displays, ornaments, and behaviors.

The process of the formation of new species, often resulting from isolation and evolutionary divergence. It is a central theme in evolutionary biology, explaining the vast diversity of life on Earth.

A way of defining species based on their inability to interbreed in natural environments and produce viable and fertile offspring. This concept emphasizes reproductive isolation as a defining feature.

A way of defining species based on physical characteristics, relying on expert observation and comparison. This approach is useful for organisms with limited genetic information or fossilized remains.

When two species cannot occupy the same niche at the same time due to competition. One species will either go extinct or change its niche to avoid competition.

The process where species evolve to use different resources or occupy different niches, allowing similar species to coexist.

A relationship where both species benefit from the interaction, with the benefits outweighing the costs.

A type of mutualism where the species are dependent on each other to survive, making the relationship essential for both.

A type of mutualism where the relationship is optional, and the species can survive without each other.

Primates, including humans, are characterized by specialized adaptations for tree life, such as excellent 3D vision, grasping hands and feet, and larger brains compared to other mammals.

Apes, a group within primates, are more adapted for swinging through trees. They have a more upright posture, are better at hanging from branches, and have more mobile arm joints, possibly evolved to help them climb down from trees.

Hominins, which include humans and our upright ancestors, are defined by their upright walking and distinct features in their teeth, jaws, and skull.

Modern humans, Homo sapiens, evolved in Africa around 200,000 years ago. We are characterized by a smaller, less robust facial structure and teeth, and our rapid global expansion in the last 50,000 years.

Human ancestors developed complex foraging strategies, such as using fire, creating tools for hunting and gathering, and selectively harvesting plants, which likely reinforced our existing adaptations.

A prolonged childhood learning period, the importance of social skills for survival, and cooperative adaptation mechanisms all contributed to the evolution of our social and cognitive abilities.

Brain size and body size do not always correlate directly. For example, dolphins have a larger brain-to-body ratio than humans.

The idea that the fossil record is not a perfect representation of all life that has ever existed, due to factors that influence the likelihood of an organism becoming fossilized.

The fossilization process is more likely to occur in environments with sediment deposition, like lakes or oceans, making organisms from these habitats more likely to be found as fossils.

Organisms with hard parts, like bones or shells, are more likely to be preserved as fossils compared to organisms with soft tissues.

The fossil record tends to have a greater representation of more recent organisms compared to ancient ones, because there has been less time for erosion and destruction.

Common organisms, due to their larger populations, have a higher chance of being fossilized compared to rare organisms.

The rapid diversification of a lineage into many new species, often triggered by new environments, adaptations, or interactions with other species.

Events where a significant portion of Earth's biodiversity is lost through mass extinction events, sometimes caused by catastrophic events like asteroid impacts or human activities.

The three main branches of life: Bacteria, Archaea, and Eukarya.

The process of using various techniques, including radioactivity, geological evidence, and molecular clocks, to establish a timescale for life's history and evolutionary events.

A gradual process of diversification through small changes over long periods, as well as sudden bursts of diversification, like adaptive radiations.