Chpt 23 Evolution and Variation in Biology

Changes in the genetic makeup of a population over generations. This change can involve the introduction of new traits, the disappearance of existing ones, or alterations in the frequency of specific genes.

The process by which organisms with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits to their offspring.

A feature that helps an organism survive and reproduce in its environment. These traits arise through genetic variation and are passed from parents to offspring.

Differences among individuals of the same species, including variations in color, size, shape, behavior, or chemical composition. These variations arise from mutations, meiosis, and crossover.

Evolutionary changes that occur within a population over a relatively short period. These changes involve shifts in the frequency of existing genes.

Evolutionary changes that result in the formation of new species, often through the process of isolation and divergence of gene pools.

A group of individuals of the same species living in a particular geographic area and capable of interbreeding.

The belief that life has always existed and will continue to exist without any beginning or end, and that life forms have remained unchanged throughout eternity.

The idea that all life forms were created by a supernatural being, with no change or evolution occurring afterwards.

The theory that catastrophic events, such as floods or meteor impacts, caused mass extinctions and created opportunities for new life forms to evolve.

The idea that life forms were not created perfect but evolved over time through a process of natural selection.

The belief that organisms gradually evolve towards greater perfection over time, driven by inherent tendencies in nature.

The first Greek philosopher to propose a theory of evolution, suggesting that nature tries to create perfect organisms but eliminates unfit forms.

A group of scientists who contributed significantly to the development of evolutionary thought, including Linnaeus, Buffon, Erasmus Darwin, Lamarck, and Charles Darwin.

The idea that changes in the environment drive organisms to evolve and adapt to those changes.

The idea that changes in the environment directly cause changes in an organism's traits, which are then passed down to offspring.

Lamarck's theory that the use or disuse of a body part can lead to its development or degeneration, and these changes are inherited.

Lamarck argued that environmental factors directly influenced the characteristics of organisms, causing them to adapt. For example, plants in shady areas develop larger leaves compared to those in sunny areas.

The idea that organisms can change gradually over time in response to their environment, eventually leading to the formation of new species.

Changes in an organism's characteristics that are caused by environmental factors or use and disuse of parts. These changes were believed to be passed on to offspring.

The concept that an organism's traits are influenced by the environment and how it interacts with it.

The idea that acquired traits are not inherited. Instead, variations arise from changes in DNA that are passed down through generations.

Darwin's theory that every cell in an organism produces particles called 'pangenes' carrying parental and acquired traits, which collect to form germ cells and transmit these traits to offspring.

This theory suggests that germ cells, not somatic cells, are the sole carriers of hereditary traits, passing them unchanged through generations.

Pangenesis was discredited because germ cells, not somatic cells, are the primary carriers of heritable traits.

Weismann's theory emphasizes that germ cells are the sole carriers of hereditary traits, unaffected by environmental influences.

Natural selection might be the cause of preserving existing forms but is debated whether it drives the evolution of new species.

It challenges the idea that only the most fit survive because 'unfit' individuals often persist.

The theory of natural selection is a powerful tool for understanding evolution but doesn't explain every aspect of the process.

Weismann's theory of germplasm continuity challenged Darwin's pangenesis, providing a more accurate explanation of inheritance.

Sudden, large changes in offspring, causing evolution. De Vries called them 'mutations'.

The distribution of organisms around the world, often due to plate tectonics, continental drift, migration, etc. Examples include Galapagos finches, Madagascar lemurs, and Hawaiian honeycreepers.

Fossil remains help reconstruct organisms and relationships between them.

The study of early development stages of organisms, revealing similarities and evolutionary relationships.

DNA sequences and genome projects help reconstruct evolutionary relationships.

Weismann's theory that the body is divided into two distinct cell lines: somatoplasm (body cells) and germplasm (reproductive cells). Somatoplasm is temporary and dies with the individual, while germplasm is immortal and passes on hereditary traits.

Somatoplasm is the cell line responsible for the body's development, growth, and differentiation of tissues. It's influenced by the environment but doesn't transmit acquired traits to offspring.

Germplasm is the cell line responsible for passing down hereditary information to offspring. It's unaffected by the environment and remains unchanged across generations.

Weismann's idea that acquired characteristics, traits gained during an individual's lifetime, are not inherited. This contradicts Lamarck's theory.

Factors within the nucleus of both somatic and germ cells that determine traits. Each somatic cell has a single factor, while germ cells contain all the factors found in the adult organism, enabling inheritance.

The theory that variations that are not heritable are simply fluctuations around the specific type, not evolutionary changes. De Vries focused on large, sudden changes in traits.

A large, sudden change in a gene, leading to a new trait. These changes are heritable and can lead to rapid evolutionary changes.

De Vries' view that small variations around the normal type are not important for evolution. He emphasized the role of mutations, not gradual variations.