02 Post Darwinism

it is the theory that suggests that offsprings are often the intermediate between their parents in features, with characteristics inherited like fluids

Theory of blending inheritance

Why was theory of inheritance rejected?

Because in this theory, variation decreases as the traits blend, meaning offsprings will not revert to show the original trait over time

Who postulated the theory of particulate inheritance

Gregor mendel

This theory states that inheritance is based on discrete particles (later called genes) that pass unaltered from generation to generation allowing variation to persist

Theory of particulate inheritance

How does the theory of particulate inheritance maintain variation?

Since particles/ genes are passed down unchanged from one generation to the next, variation can persist rather than blend away

This theory includes several theories based on the idea that organisms can inherit modifications acquired during their lifetime

Neo-lamarckism

This is the idea of straight line evolution where variation is directed toward fixed goals, leading species to evolve to a predetermined direction WITHOUT THE AID of natural selection

Orthogenesis

This is the theory that discretely different new phenotypes can arise through mutation, leading to new species without the need for natural selection

Mutationism

Who proposed the concept of mutationism

Hugo de vries, thomas hunt morgan, richard goldschmidt (redisoverers of mendel)

Who said that mutation is not an alternative to natural selection, rather its raw material

Ronald fisher

KBS Haldane

Sewall wright

True or false: Alleles are alternative forms of a gene, which ultimately come from mutations.

True

True or false: Recombination among alleles of different loci amplifies variation created by mutation.

True

True or false: Evolutionary change is a rapid process that occurs in individuals rather than populations.

False. Its gradual change

True or false: The mutation rate is fast enough to cause significant shifts in genotypic frequencies.

False. It is slow enough

Evolutionary change can be driven by two factors, what are these factors?

1. Random fluctuations ( genetic drift )

2. Non-random changes (natural selection)

True or false: Natural selection, even with slight intensity, can cause substantial evolutionary changes over time.

True

True or false: Adaptations are traits shaped primarily by random processes rather than natural selection.

False, adaptations are traits shaped by natural selection

These are alternative form of a gene, and they ultimately come from mutations

Alleles

How is variation through mutation amplified in populations?

Variation through mutation is amplified by recombination among alleles of different loci.

How does evolutionary change occur in populations?

Evolutionary change is a gradual populational process, involving changes in gene frequencies or proportions

These are traits that have been shaped by natural selection

Adaptations

True or false: Natural selection causes evolutionary change by increasing the frequency of alleles that, through recombination, lead to advantageous new phenotypes.

True

True or false: Natural populations are genetically variable because mutations can accumulate, enabling them to rapidly evolve when the environment changes.

True

True or false: Populations of the same species in different geographic localities often show no genetic differences due to natural selection.

False, Populations in different localities often have adaptive genetic differences

True or false: Differences between species or populations are often based on differences in many genes, each contributing only a small phenotypic effect, supporting the concept of gradualism.

True

True or false: Species are defined strictly by their phenotypes, not their gene pools.

False (Species are defined by gene pools, not just phenotypes)

True or false: Speciation typically results from geographic separation, leading to genetic differences due to lack of interbreeding and different selection pressures.

True

How are species defined in terms of gene pools and phenotypes?

Species are defined by their gene pools, not by phenotypes, because phenotypic variation can exist within interbreeding populations.

How does geographic separation lead to speciation?

Geographic separation leads to speciation by preventing interbreeding and subjecting populations to different selection pressures, which over time leads to genetic differences.

True or false: The accumulation of mutations alone is enough to cause rapid evolutionary changes without the influence of environmental factors.

False (Mutations provide genetic variability, but environmental changes often trigger rapid evolution)

True or false: Populations that are geographically isolated will always become separate species.

False (Geographic isolation increases the likelihood of speciation, but it doesn’t always result in new species)

True or false: Gradualism suggests that large, sudden genetic changes are primarily responsible for species differentiation.

False (Gradualism suggests evolutionary change occurs through small, incremental steps)

True or false: Gene flow between populations of a species can prevent speciation by maintaining genetic similarities.

True. ( gene flow allows for the continuous exhchange of alleles in a population, preventing reproductive isolation that could cause speciation )

True or false: All geographic separation leads to complete reproductive isolation between populations.

False (Not all geographic separation leads to reproductive isolation; some populations may still interbreed)

How does gene flow between populations affect speciation?

Gene flow between populations can prevent speciation by maintaining genetic similarities between the populations.

Does geographic separation always lead to complete reproductive isolation?

No, geographic separation doesn’t always lead to complete reproductive isolation, as some populations may still interbreed despite the separation.

Explain this concept: Gradations in phenotypic characteristics among species in the same genus, different genera, or families suggest that higher taxa arise from the accumulation of small differences over time.

if you observe subtle differences in size, shape, or behavior among species within the same genus, these variations may reflect the early stages of divergence. Over millions of years, these small differences can accumulate, leading to the formation of entirely new genera or families. This gradual process aligns with the theory of gradualism, which holds that large evolutionary changes occur in small, stepwise modifications rather than through abrupt, large-scale mutations.

True or False: Higher taxa emerge through sudden, large mutations rather than gradual accumulation of small changes.

False (Higher taxa arise through a prolonged, sequential accumulation of small differences)

True or False: The tree of life or phylogeny suggests that all living organisms descend from multiple distinct ancestors in the past.

False (All forms of life appear to have descended from a single common ancestor)

Why do gaps in the fossil records occur?

Gaps exist due to the rarity of fossilization

Explain this concept: Large evolutionary differences can occur incrementally, as shown by the fossil record, and the same forces driving population evolution can apply to higher taxa evolution.

Large evolutionary differences arise gradually over time, as shown by the fossil record, where species evolve through the accumulation of small changes. The same evolutionary forces that drive population-level changes, like natural selection, genetic drift, and mutation, also apply to higher taxonomic groups. Over millions of years, these small, incremental changes can lead to the evolution of new genera, families, and other higher taxa. This process supports the idea that major evolutionary transitions occur through gradual, rather than sudden, changes.

What do gradations in phenotypic characteristics among species of the same genus, different genera, and families suggest about how higher taxa arise?

They suggest that higher taxa arise through the prolonged, sequential accumulation of small differences rather than sudden, drastic mutations.

True or False: The concept of phylogeny implies that all life forms evolved independently of each other with no common origin.

False (Phylogeny suggests that all life forms share a common ancestor)

What process is more likely to lead to the evolution of higher taxa: the accumulation of small differences or sudden, large mutations?

The accumulation of small differences over time is more likely to lead to the evolution of higher taxa.