In secondary neurulation, 

the neural tube arises from the aggregation of mesenchyme cells into a solid cord that subsequently forms cavities that coalesce to create a hollow tube.

 

TLS Online TPP Program

#Id: 5385

#Unit 10. Ecological Principles

Populations have growth limits

Categorize these limits as being either density independent or density dependent.

TLS Online TPP Program

#Id: 5386

#Unit 10. Ecological Principles

Density-independent factors limit population size regardless of the population’s density.

Common density-independent factors include natural disasters such as tornadoes, hurricanes, floods, and fires.

TLS Online TPP Program

#Id: 5387

#Unit 10. Ecological Principles

Density-dependent factors affect population size in relation to the population’s density.

Density-dependent factors down into two categories. 

Negative density dependence 

Positive density dependence (inverse density dependence

TLS Online TPP Program

#Id: 5485

#Unit 10. Ecological Principles

Life History Strategies Incorporate Traits Relating to Survival and Competitive Ability.

TLS Online TPP Program

#Id: 5487

#Unit 10. Ecological Principles

Age at first reproduction

Earlier age →  Later age 

Clutch size

Large clutch size → small clutch size

Small size →  Large size

Trade off

TLS Online TPP Program

#Id: 5489

#Unit 10. Ecological Principles

Reproductive strategies

1.Semelparity

2.Iteroparity

Semelparity - When organisms reproduce only once during their life

Ex- insects, other invertebrates, and occurs in organisms such as salmon, bamboo grasses, and agave plants

Iteroparity - When organisms reproduce multiple times during their life.

It is common in most vertebrates and perennial plants, such as trees