A4.1 evolution and speciation Flashcards
What are three types of evidence supporting evolution?
- Molecular evidence from genetic data and amino acid sequences
- experimental evidence from selective breedin
- morphological evidence from homologous structures.
What are analogous structures, and can you provide an example?
Analogous structures are features that evolved on different branches but serve the same purpose. An example is wings in birds and insects, which enable flight but did not evolve from the same body parts.
How did Charles Darwin and Alfred Russel Wallace independently contribute to the theory of evolution?
Both Darwin and Wallace developed almost identical theories of evolution by natural selection, presenting their ideas jointly to the Linnaean Society in 1858.
Define evolution.
Evolution is the process of cumulative change in the heritable characteristics of a population, with changes passed on genetically from one generation to the next, leading to the potential emergence of new species over time.
What is Lamarckism, and how does it differ from Darwin and Wallace’s theory?
Lamarckism proposed that organisms acquire characteristics during their lifetime and pass them on. It differs from Darwin and Wallace’s theory of evolution by natural selection, where changes are heritable and occur over generations.
How did DNA evidence contribute to the support of natural selection and the development of the modern synthesis theory?
DNA evidence provided strong support for natural selection, leading to the modern synthesis theory, a combination of Darwin’s ideas with the newer concepts of genetics, confirming the role of common ancestry.
How far back in evolutionary history can your DNA include genes, and how is this demonstrated in human embryonic development?
Your DNA includes genes that trace back to a common ancestor with fish approximately 400 million years ago. In human embryonic development, slits in the neck, reminiscent of fish gills, highlight this evolutionary connection.
How do modern bioinformatic tools contribute to understanding evolutionary relationships?
Modern bioinformatic tools compare nucleic acid and protein data from various organisms, processing millions of codes to reveal differences and similarities, aiding in understanding how species are related to each other.
How can software and DNA sequence analysis be used to determine the evolutionary relationships between species?
Software, accessible online, allows the comparison of DNA sequences, such as those of the haemoglobin protein chains. Positions with matching letters indicate closeness. A specific example is the comparison of human and chimpanzee haemoglobin sequences, revealing a recent common ancestor.
In the context of DNA sequence analysis, what does an asterisk () indicate, and how is it used to determine relatedness?
An asterisk () under a position signifies that all letters in that column match. In the haemoglobin sequence, shared asterisks between humans and chimpanzees suggest a closer relationship compared to other organisms, indicating a more recent common ancestor.
Why might a line-by-line and base-by-base comparison of DNA sequences be challenging to interpret for determining relationships between species?
While informative, a detailed comparison is challenging for determining relationships. Phylogenetic trees, as shown in Figure 1, offer a clearer visualization of similarities and differences in the sequences of genes, like haemoglobin beta gene (HBB), aiding in understanding evolutionary relationships
What does the phylogenetic tree in Figure 1 reveal about the evolutionary relationships based on the haemoglobin beta gene (HBB) sequences?
The tree suggests an early speciation split between rodents and other mammals, followed by a split between dogs and primates. It illustrates the evolutionary history inferred from the haemoglobin beta gene, emphasizing that it represents only one gene among the over 20,000 genes in humans.
What is selective breeding, and what role does it play in changing domesticated animals?
Selective breeding involves choosing specific males and females to reproduce, resulting in accumulated genetic changes over generations. This process alters the characteristics of domesticated animals.
How does artificial selection differ from natural evolution in ecosystems?
Artificial selection is driven by human choice, where farmers and breeders decide which animals will reproduce. In contrast, natural evolution in ecosystems is not directed by conscious choices but occurs in response to environmental factors.
How did Teosinte transform into modern maize through artificial selection?
Farmers saved seeds from teosinte with desirable traits, leading to artificial selection over generations. This process resulted in the evolution of maize, demonstrating how controlled seed selection can bring about significant changes.
What is the significance of the transformation from teosinte to maize in terms of time scales?
The remarkable shift from teosinte to maize, driven by artificial selection, occurred in a geologically short time. Though thousands or even a hundred years may seem long to humans, in the context of species’ time scales (millions of years), these changes are relatively rapid.
What are homologous structures, and what is a notable example?
Homologous structures are derived from the same body part of a common ancestor. An example is the pentadactyl limb, with five fingers, found in diverse animals like humans, whales, and bats. Despite variations in bone shape and number, the general format remains consistent.
how did Darwin interpret homologous structures?
Darwin argued that homologous structures, like these limbs, are not coincidences but evidence of a common ancestor, indicating evolution from that shared ancestry.
What characterizes analogous structures, and can you provide an example?
Analogous structures have the same function but don’t originate from the same body part, indicating no common ancestor. An example is wings in eagles, mosquitoes, bats, and pterosaurs. Despite functional similarity, these structures don’t imply a shared ancestry.
How can analogous structures, like wings in various organisms, provide evidence for evolution?
Analogous structures, seen in diverse organisms, suggest advantageous features that could evolve in multiple ways over time. This supports the idea that similar physical aspects can arise independently, even in organisms with different phylogenies.
What characterizes marsupials, and provide an example of convergent evolution involving a marsupial?
Marsupials have pouches instead of placentas for nourishing their young. An example is the Tasmanian tiger, a marsupial resembling wolves and tigers. This showcases convergent evolution, where similar traits arise independently.
