Biology: Moths and Evolution Concepts

Hickory Horned Devil

• The Hickory Horned Devil is the caterpillar phase of the Regal Moth (Citheronia regalis)
• It is found in eastern US
• The caterpillars feed on pecan, walnut, and hickory tree leaves
• Adults do not eat
• Moths lay their eggs on leaves of trees
• Caterpillars molt four times before burrowing into the ground to pupate over winter
• They metamorphose into the Regal Moth, which lives for one or two weeks

Microevolution and Macroevolution

• Microevolution is the generation-to-generation change in populations' allele frequencies
• Macroevolution is the study of major biological changes, including the formation of new species

Biological Species Concept

• Branching evolution leads to species diversification
• Groups of interbreeding natural populations reproductively isolated from others are considered species
• Isolating mechanisms prevent interbreeding and lead to speciation

Pre-Zygotic Isolating Mechanisms

• These mechanisms prevent the formation of a zygote
• Examples include temporal isolation, geographic isolation, behavioral isolation, mechanical isolation, and gametic isolation

Post-Zygotic Isolation

• These mechanisms prevent hybrid offspring from developing or reproducing
• Examples include hybrid inviability and hybrid sterility

Allopatric Speciation

• Geographic barriers divide a population, preventing gene flow
• The Grand Canyon is a prime example, separating species of squirrels
• Storms can also result in allopatric speciation, as seen with individuals blown off a mainland onto an island

Sympatric Speciation

• New species arise without geographical isolation
• It is not common among animals, but fairly common among plants
• Genetic mutations, particularly polyploidy, are often the cause
• Polyploidy can lead to an individual being reproductively incompatible with the parent species

Polyploidy

• Extra sets of chromosomes can occur due to accidents during cell division
• Examples of polyploid species: gray treefrog and Chinese hibiscus

Tempo of Speciation

• Gradualism and Punctuated Equilibrium are two concepts associated with the tempo of speciation
• Gradualism assumes slow, continuous changes occur over long periods
• Punctuated Equilibrium proposes that evolution occurs in bursts followed by long periods of stability, making it a closer fit to the actual process of evolution

Taxonomy

• Classification system developed by Carolus Linnaeus in the 1700s
• Uses binomial nomenclature: two-part scientific name for each species
• Genus name is always capitalized and followed by the specific epithet, both written in italics

Hierarchical Classification System

• Taxonomy uses a hierarchical system to organize organisms
• From most inclusive to least inclusive:
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Classification Criteria

• Organisms are classified based on their characteristics, particularly homologous structures
• The more homologous characters shared between species, the more closely related they are

The Geological Time Scale

• Earth formed ~4.6 billion years ago (BYA)
• First prokaryotes emerged ~3.5 BYA
• Oxygen began accumulating ~2.7 BYA
• Oldest eukaryotes ~2.2 BYA
• Oldest animal fossils ~700 MYA
• Invertebrates diversified and algae diversified ~600 MYA

The Cambrian Explosion

• A period of rapid diversification, most modern animal phyla evolved ~540 MYA
• True plants originated ~500 MYA

Plate Tectonics and Biogeography

• The Earth's crust is divided into plates that move over the mantle
• Plate movement leads to geological activity, including volcanoes, mountain uplift, and earthquakes
• All landmasses formed a supercontinent called Pangea ~250 million years ago
• Plate movement influences the distribution of species over time

Biogeography

• Biogeography studies the distribution of organisms across time
• The formation of Pangea and its subsequent breakup have dramatically impacted species distribution
• Madagascar is an example of how isolation can lead to unique species diversification, with more than 50 species of lemurs evolving from a common ancestor
• Australia's isolation led to the dominance of marsupials, which are almost absent elsewhere

Continental Drift and Marsupials

• Australia's separation from other landmasses led to the unique diversity of marsupials
• Most of the world is dominated by placental mammals, making the dominance of marsupials in Australia an anomaly.

Paedomorphosis

• The retention of juvenile features in an adult organism compared to ancestral species.
• Observed in axolotl salamanders and humans.
• Human evolution involved genetic changes that slowed jaw growth relative to other skull parts.
• This resulted in an adult with childlike head proportions, larger brain case, and bigger brain due to delayed brain growth compared to chimpanzees.

Structure and Function

• The shapes and arrangements of feathers in birds create lift, smooth airflow, and aid in steering and balance, demonstrating the adaptation of old structures for new functions.

Evolution of Complex Structures

• Over 30 different species of feathered dinosaurs have been discovered through fossil records.

Explore the fascinating life cycle of the Hickory Horned Devil and delve into the principles of microevolution and macroevolution. Understand how the Biological Species Concept and pre-zygotic isolating mechanisms contribute to species diversification and speciation. Test your knowledge of these essential biological concepts.