Date of Publication

11-2024

Document Type

Master's Thesis

Degree Name

Master of Science in Biology

Subject Categories

Biology

College

College of Science

Department/Unit

Biology

Thesis Advisor

Chona Camille Vince Cruz - Abeledo

Defense Panel Chair

Ma. Carmen Ablan-Lagman

Defense Panel Member

Eric R. Punzalan
Rachel Ravago-Gotanco

Abstract (English)

The crown-of-thorns starfish (COTS) is a notorious coral predator and a significant threat to Indo-Pacific coral reefs. Despite taxonomic advancements reclassifying COTS as a complex of four genetically distinct species. While Acanthaster solaris remains nominal and is considered a synonym of A. planci, recent studies have adopted Acanthaster cf. solaris to refer to Pacific COTS. This study investigated populations from four Philippine reef sites. A total of 120 samples were analyzed through DNA barcoding using the mitochondrial COI gene to confirm species identity and image-based morphometry to document physical variations. DNA barcoding using the mitochondrial COI gene confirmed species identity through BLASTN analysis, with all samples showing 99.66–100% similarity to Pacific clade sequences in GenBank. Phylogenetic analysis further placed all Philippine COTS samples within the Pacific clade (Acanthaster cf. solaris), supported by a high bootstrap value (99%) and congruence with previously established clades. Haplotype analysis revealed connectivity between the Philippines and the broader Pacific. Seven haplotypes were shared among Philippine populations, five of which were shared with other Pacific populations, highlighting connectivity across the region. Morphological data showed significant differences in size metrics across populations, with larger individuals in Sorsogon and smaller individuals in Batangas. PCA analysis demonstrated a considerable overlap in morphological traits among populations, driven primarily by arm-to-disk ratios and spine densities. Body color variation was also not significantly associated with specific populations. These morphological patterns align with the genetic data, indicating limited differentiation among Philippine COTS populations. These findings confirm that Philippine COTS populations belong to the genetically cohesive Pacific clade (Acanthaster cf. solaris). The study highlights the need for a unified management approach to control outbreaks, while also emphasizing further research into population connectivity and larval dispersal to optimize conservation strategies for coral reef ecosystems.

Keywords: Acanthaster cf. solaris, Crown-of-thorns sea star, Morphological variations, DNA Barcoding

Abstract Format

html

Abstract (Filipino)

"_"

Abstract Format

html

Language

English

Format

Electronic

Keywords

Acanthaster; Crown-of-thorns starfish--Philippines

Upload Full Text

wf_yes

Embargo Period

1-13-2025

Download

Share

COinS