Overview of Spectroscopy Use of Physical Methods to determine structures in Organic Chemistry.
Local and regional factors determine community and population structures
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Local and regional factors determine community and population structures • Local community structure: result of the interplay of local and regional factors. • Local adaptation/population differentiation: enhanced by contrasting local conditions, prevented by ongoing gene flow. • Model system: Nature reserve “De Maten”, Genk, with its system of overflows and identical abiotic but contrasting biotic background.
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Local and regional factors determine community and population structures. Local community structure: result of the interplay of local and regional factors. Local adaptation/population differentiation: enhanced by contrasting local conditions, prevented by ongoing gene flow. - PowerPoint PPT Presentation
Transcript of Local and regional factors determine community and population structures
Local and regional factors determine community and population structures
• Local community structure: result of the interplay of local and regional factors.
• Local adaptation/population differentiation: enhanced by contrasting local conditions, prevented by ongoing gene flow.
• Model system: Nature reserve “De Maten”, Genk, with its system of overflows and identical abiotic but contrasting biotic background.
The development of a model system for study of local adaptation: Scenedesmus
Predator-induced defenceIn Scenedesmus-species• colony formation•Genetic variation present
Hypothesis: Scenedesmus genotypes from a clear pond with high grazing pressure will be bigger and show a
Stronger response to infochemicals
Isolation of Scenedesmus communities from ecologically contrasting ponds
Pond 15: clear pond withLarge Daphnia, 52 strains Pond 18: turbid pond with small
Zooplankton, 75 strains
Nature reserve“De Maten”, Genk, Belgium
Problems associated with species identification
• Description of each morphotype as distinct taxon: monograph by Hegewald & Silva lists over 1300 taxa
• Phenotypic plasticity: each genotype produces a variety of morphotypes
• Recent changes using molecular methods, 18S and ITS-region.
Molecular methods for species delineation
• 18S-rDNA RFLP
• DGGE of the ITS-2 region
• Sequence analysis of ITS-2
3´-GCGTCGGTTT TTCGACCTGAGC-5´
rDNA ITS2 gene
~ 227 - 264 bp
SSU (18S) large SSUITS 1 ITS 25.8S rDNAsmall (25-28S)
Location of the ITS spacer region on the genome
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>AJ249506>AJ237956
>AJ400496>AJ400498
>S4>S112
>AJ400493>AJ400494
>S45>S97
>AJ400499>S93>AJ400505>S104>S108>S122>S24>S27>S29>S59>S5>S62>S63>S65>S81>S94>AJ400502>S70
>S100>S101>S105>S107>S118>S16>S20>S22>S23
>S30>S36
>S42>S46>S51>S58>S60>S72>S74>S85>S86>S87>S90
>S68>S69>S96>S99>S50>S18
>S106>S11>S7>S83
>S38>S49
>S71>S9
>AJ400506>S113
>S28>AJ237959>AJ400504>S12>S114>S35>S52>S8>S98
>AJ237960>AJ237961
>AJ400495>AJ400500
>S39>S41
>AJ400503>S110>S129>S19>S33>S40>S61>S66>S6>S82>S84>S92>S95
>S64>S102>S26>S89>S25
>S44>AJ400497
>S135>S21>S37>S75
>AJ400501>AJ400492
>S34>AJ316581
>S67>AJ237958
>S10>AJ237957
>S43>S13
>S111>S47>S88
“D.communis-clade”
“D.armatus-clade”
“D.opoliensis-clade”
“D.bicellularis?-clade”
“D.brasiliensis-clade”
“Desmodesmus sp.”
Desmodesmus opoliensis
Desmodesmus armatus
Typical shape, bristles, difference between ponds
Very variable, present in both ponds
Desmodesmus communis
Present in both ponds, outer cell wall layer
Desmodesmus brasiliensis
Distinctive ribs, short spines
Desmodesmus bicellularis?
Very small, no spines, Morphologically heterogenous, only in turbid pond
Conclusions
• Agreement of morphological and molecular methods.
• Shifts in species composition though the most
abundant species are present in both ponds.
• Further work at the intraspecific level in progress
