BIOL1004 Chap.2 Evidence for Evolution and Models of Selection
Evidence for Evolution and Models of Selection
The course organises evidence into fossil, anatomical, genetic and experimental lines; strong answers state what each line independently contributes. Body fossils preserve part of an organism, whereas trace fossils preserve activity such as tracks or burrows; they answer different biological questions.
Sedimentary rock can preserve remains, while heat and transformation make igneous and metamorphic contexts much less suitable for fossil preservation. The Pilbara cross-section caption has its own 3.35-3.46 billion-year range and must not be fused with the separate 3.7-billion-year statement. The soapberry-bug field study connects host fruit structure with proboscis length across balloon vine and golden raintree environments.
Evolutionary constraint explains why modification works with inherited structures rather than designing an organism afresh. The highest-value synthesis is convergence: fossils, anatomy, sequences and experiments support common descent on different timescales.
What this chapter covers
- 01
The course organises evidence into fossil, anatomical, genetic and experimental lines; strong answers state what each line independently contributes.
- 02
Body fossils preserve part of an organism, whereas trace fossils preserve activity such as tracks or burrows; they answer different biological questions.
- 03
Sedimentary rock can preserve remains, while heat and transformation make igneous and metamorphic contexts much less suitable for fossil preservation.
- 04
Superposition orders undisturbed strata relatively, while unconformities expose missing time and explain why a fossil sequence can be incomplete.
- 05
The course gives 3.7 billion years for the earliest fossils on one page and about 3.5 billion years for the oldest fossils on another; the guide presents the conflict rather than choosing.
- 06
The Pilbara cross-section caption has its own 3.35-3.46 billion-year range and must not be fused with the separate 3.7-billion-year statement.
- 07
reconstructed from a sequence of forms at present, 30, 40 and 55 million years, with changing locomotor anatomy and vestigial pelvic structures.
- 08
Homologous forelimbs share an underlying origin despite different functions, while analogous traits share function but arose from different origins.
Chapter 2 model reasoning
- unweightedThe whale transition is reconstructed from a sequence of forms at present, 30, 40 and 55 million years, with changing locomotor anatomy and vestigial pelvic structures. The point is not the isolated label: it is how the statement contributes to matching each line of evidence to the evolutionary claim it can actually support. State the subject, process and outcome in that order, then test whether reversing any direction word would change the biological meaning. That discipline turns a remembered phrase into an explanation.
- unweightedHomologous forelimbs share an underlying origin despite different functions, while analogous traits share function but arose from different origins. Use this as a comparison rule. Name the shared feature first, then the feature that separates the cases, and finish with the evidence or observation that would let you choose between them. Avoid adding an unstated mechanism merely because it is familiar from general biology.
- unweightedHaemoglobin amino-acid similarity is genetic evidence of relatedness; genes do not alter in response to a phenotype's immediate need. Read it as a mechanism with a starting condition and a result. A complete account identifies what changes, what remains fixed and the scale at which the conclusion applies. If a number or date is not needed for that mechanism, do not let uncertain precision replace the causal explanation.
Key terms
- Body fossil
- Preserved material from an organism's body.
- Trace fossil
- Preserved evidence of an organism's activity.
- Homology
- Similarity due to shared evolutionary origin, even when function differs.
- Unconformity
- A break in a rock sequence representing missing geological time.
- Disruptive selection
- Selection favouring both extremes and acting against intermediates.
Evidence for Evolution and Models of Selection FAQ
What is the core reasoning skill in Evidence for Evolution and Models of Selection?
The core skill is matching each line of evidence to the evolutionary claim it can actually support. The highest-value synthesis is convergence: fossils, anatomy, sequences and experiments support common descent on different timescales.
Which distinction is easiest to reverse in Chapter 2?
The soapberry-bug field study connects host fruit structure with proboscis length across balloon vine and golden raintree environments. Directional selection shifts a trait distribution toward one extreme when that extreme has higher reproductive success.
What should I confirm on MyLearning for this chapter?
Use MyLearning for any missing topic pages, live assessment instructions and the complete Week Review Quiz pool. Do not extend the chapter beyond the published scope.
Exam move
Start with a closed-note reconstruction of the chapter's main relationship. Write each directional pair in both words and a small diagram, then answer the worked example without looking at the model. Use the two practice items to diagnose whether the error is vocabulary, sequence, evidence or scope.
Finish by checking the live MyLearning topic and Week Review Quiz, because this guide does not replace missing course pages or current instructions.
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