Lec 1 Flashcards
What is the definition of Biological evolution?
change in populations inherited traits occurs from one generation to the next.
What can be observed for monogenic traits in biological evolution?
Changes in allele frequencies at a particular gene.
Is Evolution “just” a theory?
No, scientific theories are backed by multiple lines of evidence and provide overarching explanations for major aspects of the natural world.
What are some examples of other scientific theories?
Gravity, Plate tectonics, and Germ theory.
Is evolutionary theory widely accepted by biologists?
Yes, evolutionary theory is overwhelmingly accepted by biologists.
What supports the evidence for evolutionary theory?
-Predictions extensively tested
-measurable evolutionary changes are sometimes observed within a human lifespan
-preserved in fossils and genomes.
How do we know whales are mammals?,
Whales share synapomorphies with mammals, including mammary glands, three middle ear bones, hair (in developing embryos), and similarities with fish arose through convergent evolution because of an aquatic lifestyle.
What is the homologous structure in whales to the forelimbs of other tetrapods?,
The pectoral fin in whales is homologous to the forelimbs of other tetrapods.
What synapomorphies do fossil whales share with modern cetaceans?,
involucrum
reduced pelvic limbs
long snouts
heterodont teeth like terrestrial carnivores.
Do evolutionary biologists search for missing links?,
No, biologists expect the fossil record to be incomplete, and finding direct ancestors is challenging even if they have been preserved somewhere.
What evidence supports relationships between current and past species?,
Available molecular, morphological, and embryological evidence
How is the cetacean transition from land to water documented?
Through isotopic analysis of fossil teeth and fossil analysis of hind limb loss.
What does isotopic analysis of fossil teeth reveal about marine animals?
marine animals have a higher O18/O16 ratio in their teeth due to their consumption of saltwater.
What happens to hindlimbs in embryos during cetacean evolution?
Hindlimbs begin to form in embryos but do not fully develop; instead, they are reabsorbed by week 9.
Is the idea that organisms are perfectly adapted to their environment true?
No, natural selection works with available genetic variation and is constrained by the laws of physics and developmental programs.
What are examples of whales with vestigial legs?
Ambulocetus is a fossil whale with legs, and Basilosaurus had vestigial legs.
Do dolphin embryos develop hind limb buds?
Yes, dolphin embryos still make hind limb buds that disappear later in development.
Does evolution happen for the good of the species?
No, natural selection operates on traits that are beneficial for individuals or their genes in a particular environment.
What happens to traits that are bad for individuals?
Traits that are bad for individuals (or genes) will not be selected for, even if they would be good for the species.
What is the result of competition for mates?
Competition for mates can lead to sexual selection, promoting the evolution of certain traits.
What is one reason for the evolution of large brains?
Sociality, as forming lasting alliances through kin selection and complex communication required a large brain.
Are organisms perfectly adapted to their environment?
No, natural selection works with available genetic variation and is constrained by the laws of physics and developmental programs.
Why do whales have a large brain size relative to other vertebrates?
complex social behavior and language but comes at a high metabolic cost.
What lineage of whales lost teeth and developed baleen?
The Mysticetes lineage of whales lost teeth and completely replaced them with baleen.
