🌟 “Speciation Station: How New Species Are Born!”

📚 Organized Notes with Headings, Diagrams, and Bold Terms

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🔹 What is a Species?

• A species is a group of interbreeding individuals that produce fertile offspring in natural conditions.
• They share common characteristics and a genetic identity.
• Identification by physical traits is sometimes misleading due to cryptic species (appear similar but are genetically different).

✅ Biological Species Concept (Ernst Mayr):

“Groups of interbreeding natural populations that are reproductively isolated from others.”

• Reproductive isolation means members of different species don’t mate or produce fertile offspring.

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🔸 What is Speciation?

• Speciation is the process where new species evolve from a common ancestor.

• Requires:

  • Genetic divergence

  • Reproductive isolation

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🔶 Types of Speciation (Modes)

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1️⃣ Allopatric Speciation

📍 "Separated by barriers"

🧭 Definition: A population is geographically divided (e.g., by mountains, rivers).
Each group evolves separately.

🧪 Key Term: Geographical isolation

💡 Example: Darwin's finches on Galápagos Islands

📊 Diagram:

csharp
Original Population
        ↓
[Geographical Barrier]
        ↓
Two Isolated Populations
        ↓
Independent Evolution → New Species

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2️⃣ Peripatric Speciation

🌱 "Small group splits off"

🧭 Definition: A small population becomes isolated at the edge of a larger one.
Evolves rapidly due to founder effect and genetic drift.

🧪 Key Term: Founder effect (small group, limited genes)

💡 Example: Island species from small founding populations

📊 Diagram:

pgsql
Large Population
    ↓
Small group moves to a new area
    ↓
Isolation + rapid change
    ↓
New species evolves

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3️⃣ Parapatric Speciation

🌍 "Side-by-side populations"

🧭 Definition: Populations live next to each other but in different environments
(like soil types or pollution levels).

🧪 Key Term: Environmental gradient

💡 Example: Grass species Anthoxanthum odoratum in different soil types.

📊 Diagram:

css
Population A ←———→ Population B
(different soils, limited gene flow)
        ↓
   Adaptation to local conditions
        ↓
  Reproductive isolation develops

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4️⃣ Sympatric Speciation

🏞️ "Same place, new species"

🧭 Definition: New species form in the same area without physical barriers.
Happens due to:

• Polyploidy (common in plants)

• Niche differentiation (different roles/resources)

🧪 Key Terms:

• Polyploidy = Extra sets of chromosomes

• Niche = Role or resource use

💡 Example: Some plants form new species through polyploidy.

📊 Diagram:

scss
One population in same area
     ↓
Genetic mutation (e.g. polyploidy)
     ↓
Instant reproductive isolation
     ↓
New species

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🎯 Flashcard-Style Review

🔍 Term	🧠 Definition
Species	Group of organisms that can interbreed and produce fertile offspring
Speciation	Formation of new species through evolution
Reproductive Isolation	Mechanisms preventing species from interbreeding
Allopatric Speciation	Speciation due to geographical separation
Peripatric Speciation	Small, isolated group forms new species
Parapatric Speciation	Adjacent populations evolve into new species
Sympatric Speciation	New species evolve in the same geographical area
Polyploidy	Extra chromosome sets lead to speciation (common in plants)
Cryptic Species	Look alike, genetically different Related Posts Class Mammalia Viruses& Clasification Biodiversity And Measurements