Klasifikasi Interaksi Spesies
Interaksi populasi dapat dikelompokkan berdasarkan mekanisme interaksi atau efek dari interaksi
Ada 6 macam tipe interaksi yang terjadi antara individu-individu pada spesies yang berbeda berdasarkan mekanismenya
Enam tipe interaksi:
Kompetisi
Competition is the outcome of shared, limiting resources
Sharing implies that the species share resources that are important to their ecological success
Not all individuals of each competing species will receive sufficient resource to maximaze their survival and reproduction (thus the use term of the limiting)Notice that they do not need to die directly, only overall performance must be reduced
Kompetisi Intraspesific Vs Interspesific
Both types can affect individual (doesn’t matter who ate the food if it is gone)
If competition arises out of the need for resource, the organism most likely to need a resource one competitor wants is another individuals of the some species)
Scramble (resource) competition
No need for individual to interact directly, as each takes from a common resources
Each competitor affect all other competitors by reducing the amount of resource available to others
Schoener divided this into:
Exploitative – consumption of the same food item or abiotic resource
Preemtive – taking space on a surface needed for living (rocks for mussels, land for plant, etc)
Interference (contest) competition
Competitor interact directly, outcome of one contest need not affect any other competitors
Competition for territory
Inhibitory chemicals
Contest for individual resource items
Kompetisi Intraspesies
Density and Stress
Dispersal
Social Interactions
Social dominance
Territoriality
Home range
Density and Stress
Increased density can result increased social stress
Stress in animal, evidence suggests, can act on the individual through a physiological feedback involving the endocrine system
Stress triggers hyperactivation of the hyphothalamus pituitary-adrenocorticular system, which in turn alters gonadotrophic secretions.
Such profound hormonal changes result in a suppression of growth, a curtailment of reproductive functions, and delayed sexual activity.
Further, these hormonal change may supress the immune system and cause breakdowns in white blood cell, increasing an individual vulnerability to disease
Social stress among pregnant female may increase intrauterine mortality and cause inadequate lactation and subsequent stunting of nurslings
Thus stress can result in decreased births and increase mortality
Dispersal
Social pressure and crowding may also induce emigration or dispersal
Dispersal appears to be density-independent except at the highest population levels;most dispersal appears to take place when populations are increasing rather than at the peak population levels.
Dispersal may function in population regulation by encouraging mostly subaduls and subdominant individuals to leave their natal area and occupy vacant habitats
Although risk of moving are great, successful dispersing individuals, which may be genetically programmed to do so, improve their fitness
Social Interaction
Aggressive or agonistic interaction are the basis of social organization, which take two form: dominance and territoriality
Dominance, based on individual distance (the distance from an other individual that provokes aggression or avoidance behavior) and a set of relationship, result in space being shared among individuals.
Territoriality involves the division and exclusive occupation of space by a social unit or an individual with a defended boundary
Social Dominance
Based on intraspesific aggressiveness and intolerance and on the dominance of one individual over an other
Two opposing forces are at work simultaneously: mutual attraction versus sosial intolerance, a negative reaction againts crowding
(a) one direction
(b) triangular
(c) complex dominace
Dominansi pada kelompok singa
Kompetisi Interspesifik
Interaksi Interspesies
Kompetisi
Kompetisi merupakan hasil dari pembagian (shared), sumberdaya yang terbatas (limiting resources)
Sharing menunjukkan bahwa spesies berbagi sumberdaya yang sangat penting untuk menunjang keberhasilan ekologis.
Tidak semua individu spesies yang berkompetisi akan mendapatkan sumberdaya yang cukup untuk memaksimalkan kelangsungan hidup (survival) dan reproduksinya (maka digunakan istilah limiting atau terbatas).
Catatan bahwa spesies yang berkompetisi tidak akan mati secara langsung, hanya performance secara keseluruhan akan berkurang.
Amensalisme: interaksi yang terjadi antara dua spesies dimana satu spesies rugi sedangkan spesies yang lain tidak mendapatkan keuntungan:
Saat babi liar mencari makan, akan merusak lapisan teratas tanah, dan beberapa organisme akan keluar dari liangnya dan lebih mudah dimakan oleh predatornya, walaupun hewan penggali lubang rugi, babi tidak mendapatkan keuntungan dari situasi tersebut.
Allelopati: pelepasan toksin ke dalam lingkungan
Bisa situasi dimana suatu spesies rugi dengan pelepasan toksin, tetapi spesies yang melepaskan toksin tidak mendapatkan keuntungan (pada kasus ini disebut amensalisme)
Bisa berupa spesies yang melepaskan toksin mendapatkan keuntungan dari toksin yang dikeluarkannya (penghindaran diri dari predator atau kompetisi dengan spesies lain)
Simbiosis: (living in intimate contact) dapat terjadi dalam bentuk: interaksi mutualisme, komensalisme dan parasitisme.
Mutualisme
Hubungan antara dua organisme yang saling menguntungkan keduanya
mutualisms carry both costs to each partner and benefits as well
mutualisms are favored when the benefits are greater than the costs, so it is the net benefits (or benefit cost ratio) that determine the outcome of these interactions
Obligat - organisme tidak dapat survive tanpa kehadiran organisme partnernya
Fakultatif: organisme dapat hidup tanpa kehadiran organisme yang lain (partner dalam interaksinya)
Contoh Mutualisme:
Penyerbukan:
Pollinator mendapat:
Makanan (nektar, polen, makanan berenergi tinggi atau berprotein)
Bahan untuk sarang – lebah mendapatkan lilin untuk membuat sarang
Tumbuhan mendapat:
Transfer polen lebih efisien (compared to wind)
Menghindari inbreeding
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