- Human activities increasingly influence the structure and function of ecosystems, altering the delicate balance between organisms and their environments.
- To assess the extent of these impacts, ecologists study three key aspects of species:
- Classification: understanding the species’ position in the ecosystem and food web.
- Niche requirements: understanding how and where it lives, including its resource use and environmental conditions.
- Life cycle: understanding how it grows, reproduces, and interacts with environmental factors.
Climate Change and Disruption of Life Cycles
- Human activities, particularly the burning of fossil fuels, deforestation, and industrial emissions, are causing significant climate alterations.
- Climate change alters seasonal temperature patterns, rainfall, and photoperiod cues, which are critical triggers for reproductive and migratory behaviors.
Phenological Shifts
- Changes in temperature and day length patterns lead to earlier flowering, fruiting, breeding, or migration.
- Species adapted to seasonal cycles are now experiencing mismatched ecological cues, disrupting feeding and reproductive success.
- Many temperate plants now flower weeks earlier than in past decades due to warmer springs.
- This shift can cause pollination mismatches, when pollinators like bees or butterflies have not yet emerged, leading to lower seed production.
Trophic Mismatches
- Temperature changes can desynchronize interdependent species across trophic levels (producers, consumers, predators).
- When prey species emerge earlier than predators, food shortages occur at critical breeding times.
- The pied flycatcher migrates to Europe in spring to feed on caterpillars.
- With warmer springs, caterpillars now peak earlier, leaving the flycatcher without sufficient food to feed its chicks, reducing reproductive success and population size.
Arctic and Polar Ecosystems
- Melting ice from global warming alters the seasonal cycles of polar species.
- Polar bears, for example, rely on sea ice to hunt seals.
- Shorter ice seasons reduce feeding opportunities, leading to lower fat reserves, affecting reproductive rates and cub survival.
Reduced ice cover in the Arctic has shortened polar bear hunting seasons by weeks, directly impacting their ability to reproduce and sustain energy through summer fasting periods.
Habitat Destruction and Fragmentation
Habitat loss from urbanization, deforestation, and land conversion disrupts the continuity of ecosystems that many species rely on during their life cycles.
Impact on Breeding and Migration
- Sea turtles return to specific beaches to lay eggs. Coastal development and artificial lighting disorient hatchlings and destroy nesting grounds.
- Migratory birds lose stopover sites due to urban sprawl and deforestation, making long-distance migration impossible.
- Amphibians, such as frogs, rely on wetlands for breeding. The loss or pollution of these habitats leads to reduced larval survival and population decline.
