Species, sociality and interactions

What is a species? Biological species: Individuals that interbreed to produce viable, fertile offspring and are reproductively isolated from others Morphological species: individuals group based on morphological or even physiological similarities Phylogenetic species: a group of individuals that because of their relatedness, share at least one morphological or molecular trait that is absent in other potentially related groups (in other words: a shared derived trait)

Variation and other differences lead to species coexistence Gause principle: species cannot coexist for long if use of resources is too similar (i.e. if ecological niches overlap too much ) Species either: partition resources (may be evolutionary adaptations or behavioral modification), or one goes extinct J. Kim 2009

Intraspecific and interspecific coexistence Coloniality: large nesting colonies (1 or more species) Benefits: individual risk of predation is lower, more protection for nestlings Costs: competition for space, food, diseases, catastrophes

Species can avoid competition by partitioning resources (niche space) in many ways :  Horizontal habitat  Vertical habitat  Nest site  Food type  Timing of resource use (day/night, season)  Body size

Vertical habitat partitioning Myrmotherula antwrens Terborgh 1990

Micrastur ruficollis (MIRU) Micrastur semitorquatus (MISE) Micrastur mirandollei (MIMI) Micrastur buckleyi (MIBU) Micrastur gilvicollis (MIGI) Forest-falcons (Micrastur : Falconidae)

Terra firme forest Floodplain forest

Primary forest

Research Questions Understanding the patterns of habitat use of Forest-falcons Hypothesis: Overlap in habitat use should be small to facility coexistence of Forest-falcons Prediction 1: I expect to see species affinity for certain habitats Prediction 2: I expect to see differences in the intensity of use of habitat

Captures Mistnets Balchatris Cavity traps

Body measurements and attachment of radio-transmitters

Location by triangulation: from the ground and canopy LOAS, ArcGIS software home ranges, utilization distributions (UD)

Captured birds SpeciesAdults Capt. Tagged Young Capt. Tagged MIRU MIGI MIBU 3 3 MIMI MISE

Capture locations

Intraspecific range overlap MIRU

Intraspecific UD overlap MIRU Pedro Han Solo Lucky Pedro ha,18% ha, 3.9%

Intraspecific range overlap MIGI

Oli Sofia Millennium Maggie Intraspecific UD overlap MIGI 5.75 ha, 2.5% ha, 0.69%

Interspecific range overlap MIRU MIGI

MIMI and MIBU ranges MIBU MIMI

Speciation Why there are some many different species? How does speciation occur?

Speciation Why there are some many different species? G.E. Hutchinson: One possible answer: to avoid competing for similar resources (food, habitat, etc.) Speciation: result of evolutionary processes that result in divergence of a new species from a common ancestor (one species splits in two) Speciation: result of natural selection, isolation, adaptive radiation

Geographic patterns of speciation Allopatric Peripatric Parapatric Sympatric Original Population Initial step of isolation Evolution of reproductive isolation New distinct species after determination of new ranges Barrier formation Within the habitat In adjacent habitat In isolated habitat In isolation New habitat Genetic change New habitat

But…. there is still species variation Differences on bill dimensions and body coloration of local populations Bill size adapted to food and local environments (Zink 1986)

Intraspecific and interspecific coexistence Cooperation: several individuals related or not function as a group for certain activities Breeding: several individuals attending one nest or more (i.e Superb Starlings in east Africa) Benefits: higher nesting success, less risk of predation Costs: reproductive conflict and cost in social status. females compete for mates too (they look the same as males (Rubenstein et al. 2009, Rubenstein and Shen 2009)

Intraspecific and interspecific coexistence Hunting and foraging: several individuals take part in the search of food Benefits: higher success accessing to resources, or trapping food Costs: social status may determine the access to the resource even if helped obtaining it

Foraging in groups Monospecific and multispecies Mixed species flocks: canopy, understory (hierarchies determine the diversity and abundance of members) =related

Other associations Primates and birds: (insects scared by monkeys are taken by birds, others take seeds or fruits dropped while the troop is passing) Egrets and cattle (Butler 2008): (regardless of habitat or time of day, larger groups alone vs. smaller when feeding with cattle (more successful) More success with cattle vs. buffalo

Birds and other mammals, including bipedal primates!

More social interactions Army ants and Ant birds: army ants (Eciton burchelli), go on raids and birds take anything the ants scared on their raid

How do organisms compete for resources? Exploitation: use resources so efficiently that others do not get them Interference: Actively prevent others from using resource, or make it so energetically costly that use of that resource is not worthwhile for others