Social and genetic structures, spatial use patterns and phenology of the Lesser Cuckoo Cuculus poliocephalus

다국어 초록 (Multilingual Abstract)

Spatial use pattern, social and genetic structure, and environment factors are often closely related each other, and are also most important factorsto understand ecology of organisms. Lesser cuckoos, Cuculus poliocephalus, are one of avian brood parasites, which depend their reproduction to other host species by laying eggs to host nest. This species has been rarely investigated about its detailed ecology yet. The aims of this thesis are to determine spatial pattern, social and genetic structure and climate change impacts of lesser cuckoos.
In chapter 2, I investigated the social system of lesser cuckoos, by using a comprehensive approach, including field observation, radio-tracking, and genetic analyses. I found that genetically unrelated, multiple males and females coexist in a single area, and radio-tracking confirmed that this co-occurrence was neither temporary nor arbitrary. Instead, sympatric cuckoos appeared to share their home ranges and often chased each other for mating without antagonistic physical interactions. I concluded that the lesser cuckoo may employ a scramble competition mating system without territoriality and this unusual mating system in higher vertebrates may have arisen due to the absence of parental care.
In chapter 3, sexual differences of habitat use patterns in lesser cuckoos were revealed using compositional analysis. Lesser cuckoos showed broad home ranges more than other parasitic cuckoos. I deduced that broad home ranges of lesser cuckoos were may regarded as because of emancipation from spatial constraints, non-territoriality and mosaic available breeding areas. At the study area levels, there was no significant difference between compositions of male and female home ranges, but these compositions were non-randomly choose. They preferred field and grassland, where are available breeding and foraging resources. At the home range level, males and females showed significantly different habitat compositions in core use area with that females
more preferring forest type than males. I discussed the role of sexual conflicts and host and food availabilities as reasons for the different habitat preferences between sexes.
In chapter 4, I showed whether there is genetic differentiation between two color plumage morph groups of female lesser cuckoos to confirm whether plumage coloration is determined by maternal inheritance. Because bird mtDNA is highly related to W chromosome, and they are major factors of maternal inheritance in birds, so each mtDNA ofstudied cuckoos wassequenced. I estimated genetic distances between two color morph
females using Kimura 2-parameter model. I found no genetic differentiation in mtDNA between two color morph females. Consequently, I showed no relationship between female plumage coloration and maternal inheritance caused by mtDNA. To define color determinant mechanism, it is necessary to reveal effects of other genetic, physiological and behavioral factors to plumage coloration.
In chapter 5, I predicted the distribution shift of an avian brood parasite, the lesser cuckoo and its announced 12 host species according to climate change scenarios to test spatial effect of climate change. Using species occurrence data (presence-only) and environmental variables obtained from publicly available databases, I developed species distribution models under the current and future climate conditions and then compared
how much their ranges and the overlap between the cuckoo and hosts are predicted to change owing to climate change. The amount of suitable habitats for the lesser cuckoo and for most host species was predicted to decrease, all the while the ranges generally shifted northward. Climate change also decreased the amount of overlap between the lesser cuckoo and its hosts. This is a mechanism that may significantly shrink the realized range of the lesser cuckoo and should therefore be taken into account in range projections.
These results provide evidence that climate change affects cuckoos not only through altered abiotic factors but also because cuckoos and hosts could react differently to such changes, jeopardizing the ability of parasites to track their climate envelope.

목차 (Table of Contents)

• 1: General Introduction 1
• 2: Space use, home range overlap and its genetic correlates in the lesser cuckoo 6
• 2.1. Introduction 6
• 2.2. Methods 9
• 2.2.1. General fieldwork 9
• 2.2.2. Radio-tracking 10
• 2.2.3. Data analysis 13
• 2.2.4. Genotyping 15
• 2.2.5. Genetic analysis 17
• 2.3. Results 18
• 2.3.1. Number of cuckoos captured 18
• 2.3.2. Home range and its overlap 20
• 2.3.3. Diurnal change in space use 23
• 2.3.4. Genetic association of sympatric males 25
• 2.4. Discussion 28
• 3: Habitat selection in the lesser cuckoo, an avian brood parasite breeding on Jeju Island, Korea 32
• 3.1. Introduction 32
• 3.2. Methods 34
• 3.2.1. Fieldwork and radio-tracking 34
• 3.2.2. Defining the study area and home range 35
• 3.2.3. Classifying habitat types 36
• 3.2.4. Quantifying habitat composition 37
• 3.2.5. Assessing habitat preference 38
• 3.3. Results 40
• 3.3.1. Habitat composition of the study area 40
• 3.3.2. Habitat selection at home range: second-order selection 42
• 3.3.3. Habitat selection in the core-use area: third-order selection 44
• 3.3.4. Diurnal changes in habitat selection 46
• 3.3.5. Habitat preferences 48
• 3.4. Discussion 50
• 4: Female-specific dimorphism of brood parasitic cuckoos is not associated with the mitochondrial DNA 53
• 4.1. Introduction 53
• 4.2. Methods 56
• 4.2.1. Cuckoo samples 56
• 4.2.2. mtDNA sequencing 57
• 4.2.3. Analyzing genetic distance between two color groups 58
• 4.3. Results 59
• 4.4. Discussion 64
• 5: Host-parasite interaction augments climate change effect in the lesser cuckoo 66
• 5.1. Introduction 66
• 5.2. Methods 70
• 5.2.1. Study species 70
• 5.2.2. Species occurrence data 71
• 5.2.3. Environmental data 72
• 5.2.4. Species distribution models 74
• 5.2.5. Species responses to climate change 75
• 5.3. Results 76
• 5.3.1. Model performance and importance of variables 76
• 5.3.2. Distributional responses under climate change 77
• 5.3.3. Overlapping responses between the cuckoo and host species 83
• 5.4. Discussion 86
• 6: General Discussion 89
• REFERENCES 94
• APPENDIX I 114
• APPENDIX II 120
• ACKNOWLEDGMENTS 124