Primary neurulation can be divided into four stages:

1. Elongation and folding of the neural plate

2. Bending of the neural plate

3. Convergence of the neural folds

4. Closure of the neural tube

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

TLS Online TPP Program

#Id: 5490

#Unit 10. Ecological Principles

Iteroparity - Repeated reproduction at intervals throughout the life cycle. It is common in most vertebrates and perennial plants, such as trees

TLS Online TPP Program

#Id: 5491

#Unit 10. Ecological Principles

Type of iteroparity

Seasonal iteroparity- Many species, such as birds or mammals, or temperate forest trees, have distinct breeding seasons Continuous iteroparity- individuals reproduce repeatedly and at any time of the year. 

TLS Online TPP Program

#Id: 5492

#Unit 10. Ecological Principles

TLS Online TPP Program

#Id: 5493

#Unit 10. Ecological Principles

If survival of juveniles and adult is poor - Selection favors a single act of reproduction