Q2 - GenBio2 🌱 Flashcards
Is the process by which different species of organisms have developed and diversified from earlier forms throughout the history of the Earth.
Evolution
Various lines of evidence support the theory of evolution, demonstrating how life on Earth has changed over time.
Evolution
Evidences of Evolution (5):
- Fossil Evidence
- Anatomical Evidence
- Geographic Distribution of Species
- Molecular Biology
- Embryology
____ are one of the most direct pieces of evidence for evolution. They provide tangible proof that organisms from the past differ significantly from those found today and illustrate a gradual progression of evolution over millions of years.
Fossils (Fossil Evidence)
By determining the age of fossils and categorizing them from various global locations, scientists can establish a timeline of when different organisms lived relative to each other.
The fossil record reveals the evolutionary history of species, including detailed evidence of the evolution of humans and horses, showing how species have adapted and evolved over time.
FOSSIL EVIDENCE
____________ provide crucial evidence for evolution, especially through the study of homologous and vestigial structures
ANATOMICAL STRUCTURES/EVIDENCE
Anatomical structures provide crucial evidence for evolution, especially through the study of ____ and ____ structures
homologous
vestigial
These are structures in different organisms that share the same basic form due to descent from a common ancestor.
Homologous Structures
For example, the bones in the limbs of humans, dogs, birds, and whales have a similar overall construction, despite differences in shape and size that evolved over time. This similarity indicates a shared evolutionary origin.
Homologous Structures
These are remnants of structures that were functional in an organism’s ancestors but have lost their original function in modern species.
Vestigial Structures
Examples include the wings of flightless birds, hind leg bones in whales, and the human appendix. ____________ serve as evidence of evolutionary change, reflecting a species’ evolutionary history.
Vestigial Structures
This occurs when unrelated species develop similar traits due to similar environmental pressures, not because of a shared ancestry.
Convergent Evolution
For instance, the arctic fox and ptarmigan both have white winter coats to blend in with snowy environments, despite not being closely related. This phenomenon demonstrates how natural selection can lead to similar adaptations in different species.
Convergent Evolution
The ____________________ supports the theory of evolution, particularly when considered alongside the movement of tectonic plates.
Geographic Distribution of Species
Geographic Distribution of Species
Species that evolved before the breakup of the supercontinent Pangaea are found across the globe, while those that evolved after its breakup are often unique to specific regions.
Global Distribution
Geographic Distribution of Species
For example, the distinct plant and animal species in Laurasia (northern continents) and Gondwana (southern continents) emerged after these landmasses separated.
Global Distribution
Geographic Distribution of Species
Australia’s long isolation, for instance, has led to the great diversification of marsupials and the absence of other mammals.
Isolation & Endemism
The abundance of endemic species—species found nowhere else—is typical of islands and isolated regions, where species evolve independently, resulting in unique evolutionary paths.
Isolation & Endemism
MOLECULAR BIOLOGY (3):
- Universal Genetic Code
- DNA Similarities
- Gene Duplication & Evolution
The universality of DNA as the genetic material, along with the near-universal genetic code and DNA replication machinery, strongly indicates a common ancestor for all life on Earth.
Universal Genetic Code
The relatedness of organisms is reflected in the similarity of their DNA sequences, which align with the patterns expected from descent with modification. Closely related species have more similar DNA, supporting their common ancestry
DNA Similarities
DNA sequences also shed light on evolutionary mechanisms, such as the evolution of new protein functions following gene duplication events. One gene copy can mutate and evolve new functions, while the other maintains its original role, facilitating evolutionary innovation.
Gene Duplication & Evolution
EMBRYOLOGY (2):
- Conserved Developmental Stages
- Vestigial Embryonic Structures
Early embryonic development tends to be conserved across different species, reflecting their shared evolutionary history. For example, all vertebrate embryos, including humans, exhibit gill slits and tails during early development. These features disappear in adult terrestrial species but are retained in adult aquatic species, such as fish and some amphibians.
Conserved Developmental Stages
Some structures appear during embryonic development but disappear before the organism reaches adulthood. For instance, great ape embryos, including humans, develop a tail structure that is lost by birth. These vestigial embryonic structures provide insight into the evolutionary past of species.
Vestigial Embryonic Structures
Conclusion: Evidence for Evolution
The evidence for evolution is extensive and diverse, coming from multiple fields of study, including paleontology, anatomy, biogeography, molecular biology, and embryology. Fossil records, anatomical similarities, the distribution of species across the globe, molecular structures, and embryonic development all provide compelling support for the theory of evolution, illustrating how life on Earth has evolved and diversified over millions of years. These lines of evidence collectively reinforce the understanding of evolution as the fundamental process shaping the diversity of life on our planet.
Misconceptions of Evolution (6):
- Evolution is “Just a Theory”
- Evolution Proposes that Life Originated by Chance
- Humans Evolved from Monkeys
- Evolution is Goal-Oriented
- Individuals Evolve during their Lifetime
- Evolution is Incompatible with Religion
Clarification:
In scientific terms, a theory is a well-substantiated explanation of some aspect of the natural world that is supported by a large body of evidence.
The theory of evolution, like the theory of gravity or germ theory, is based on extensive research, observation, and experimentation. It has been repeatedly confirmed by evidence from various fields, including genetics, paleontology, and comparative anatomy.
Evolution is “Just a Theory”
Why “Evolution is ‘Just a Theory’” persists?
The word “theory” has different meanings in everyday language and in science, leading to confusion.
In everyday use, a theory might mean a speculative idea, but in science, it represents a comprehensive explanation of facts and observations.