BIODIVERSITEIT EN ECOLOGIE VAN
INVERTEBRATEN
INTRODUCTION
Biodiversity: “… the sum total of all biotic variation from the level of genes to ecosystems”
- The term and concept of biodiversity was coined in 1986
Today: about 1.75 million species are known + between 7 and 20 species still need to be
discovered
Biodiversity comprises 3 hierarchical levels
- Ecological diversity: the variety of different ecosystems
- Organismal diversity: the number of species
- Genetic diversity: the genetic difference within and between species
Invertebrates:
There is no centralized database where all the species are organized, it’s not known how many
species exactly have been discovered
- Different studies show different numbers for the species, depending on the study and
which methods have been used
Importance of biodiversity
- Biodiversity provides essential goods and services to human societies
,How is biodiversity threatened?
- Extinction rates in vertebrates and vascular plants: estimated to be 50-100 times higher
than the natural background
- 5 – 20% of the known species are threatened with extinction in the near future
- Extinction caused by human activities: started during prehistoric times → humans
colonized the islands of the Indo-Pacific, accompanied by pigs, dogs and rats
- The local species didn’t have any predators before the invasive species came along
- About a quarter of the world’s bird species may have gone extinct during that time
- More than 650 plant and >480 animal species got extinct since 1600
What is a species?
Biological species: a group of interbreeding natural populations that do not successfully mate or
reproduce with other such groups (and sometimes they occupy a specific niche) → popular
definition but difficult + not practical to use
Morphological species: the smallest natural populations permanently separated from each
other by a distinct discontinuity in heritable characteristics (morphology, behavior,
biochemistry, …) → most used definition, more practical to use
Phylogenetic species: the smallest group of organisms that diagnostically distinct from other
such clusters and within there is parental pattern of ancestry and descent → will give rise to
recognition of many more species than more traditional concepts
Cryptic species: have very similar morphological features but are still different species, they
have genetic differences
- DNA barcoding: identifying species based on a specific DNA sequence → marker gen
The tree of life: 3 domains of cellular life
- This course: Metazoans
,Metazoans
Hypotheses of animal phylogeny based on morphological and developmental data
Hypotheses of animal phylogeny based on molecular data
Every phylogeny is a hypothesis, with new studies and methods these hypotheses can change
, Body symmetry
Radial symmetry: dipoblastic animals with 2 germ layers; ectoderm and endoderm
Bilateral symmetry: tripoblastic animals with 3 germ layers; ectoderm, endoderm and
mesoderm
INVERTEBRATEN
INTRODUCTION
Biodiversity: “… the sum total of all biotic variation from the level of genes to ecosystems”
- The term and concept of biodiversity was coined in 1986
Today: about 1.75 million species are known + between 7 and 20 species still need to be
discovered
Biodiversity comprises 3 hierarchical levels
- Ecological diversity: the variety of different ecosystems
- Organismal diversity: the number of species
- Genetic diversity: the genetic difference within and between species
Invertebrates:
There is no centralized database where all the species are organized, it’s not known how many
species exactly have been discovered
- Different studies show different numbers for the species, depending on the study and
which methods have been used
Importance of biodiversity
- Biodiversity provides essential goods and services to human societies
,How is biodiversity threatened?
- Extinction rates in vertebrates and vascular plants: estimated to be 50-100 times higher
than the natural background
- 5 – 20% of the known species are threatened with extinction in the near future
- Extinction caused by human activities: started during prehistoric times → humans
colonized the islands of the Indo-Pacific, accompanied by pigs, dogs and rats
- The local species didn’t have any predators before the invasive species came along
- About a quarter of the world’s bird species may have gone extinct during that time
- More than 650 plant and >480 animal species got extinct since 1600
What is a species?
Biological species: a group of interbreeding natural populations that do not successfully mate or
reproduce with other such groups (and sometimes they occupy a specific niche) → popular
definition but difficult + not practical to use
Morphological species: the smallest natural populations permanently separated from each
other by a distinct discontinuity in heritable characteristics (morphology, behavior,
biochemistry, …) → most used definition, more practical to use
Phylogenetic species: the smallest group of organisms that diagnostically distinct from other
such clusters and within there is parental pattern of ancestry and descent → will give rise to
recognition of many more species than more traditional concepts
Cryptic species: have very similar morphological features but are still different species, they
have genetic differences
- DNA barcoding: identifying species based on a specific DNA sequence → marker gen
The tree of life: 3 domains of cellular life
- This course: Metazoans
,Metazoans
Hypotheses of animal phylogeny based on morphological and developmental data
Hypotheses of animal phylogeny based on molecular data
Every phylogeny is a hypothesis, with new studies and methods these hypotheses can change
, Body symmetry
Radial symmetry: dipoblastic animals with 2 germ layers; ectoderm and endoderm
Bilateral symmetry: tripoblastic animals with 3 germ layers; ectoderm, endoderm and
mesoderm
