International Journal of Marine Science, 2025, Vol.15, No.2, 107-117 http://www.aquapublisher.com/index.php/ijms 113 2021). Studies have found that during the Post-Glacial Age to the Cambrian period, rapid radiation occurred in multiple algae phyla, which significantly improved the primary productivity of the ocean. At the same time, supercontinental division, sea level changes and transformations in paleomarine chemistry (such as increased oxygen content) have also created opportunities for the expansion of algae's ecological niche. Another critical period was the Cretaceous period (about 100 million years ago), when the earth's carbon dioxide concentration was high, and groups such as diatoms and dinoflages flourished rapidly, having a profound impact on the global carbon cycle (Strassert et al., 2021). After the mass extinction event about 65 million years ago, algae (especially diatoms) seized ecological spaces and continued to diversify, showing strong adaptability. These associations suggest that the evolution of algae lineages is not an isolated process, but a history of interweaving with changes in geophysical and chemical conditions. 6.3 Spatial and time background of evolutionary explosion and ecological adaptation Algae have undergone multiple evolutionary bursts and ecological adaptation stages at different temporal and spatial scales. For example, the warm period of the Cambrian climate promoted the increase of soluble nutrients and the prosperity of photosynthetic microorganisms. Changes in paleomarine transparency and nutrient configuration also promote differentiation of different groups: the advantages of large algae under low temperature and high nutritional conditions, while clean and transparent seas are conducive to the expansion of phytoplankton algae (Ho and Duchêne, 2014). Geographic isolation (such as continental drift to form ocean current partitions) promotes the speciesization of algae species. In addition, biological interactions within the biological world often accelerate the evolutionary innovation of algae under environmental pressure. Overall, the time frame and geological historical background of algae lineage evolution reflect the combined effect of multiple factors of climate, geological and ecological, and each major turning point lays the foundation for the current status of algae diversity. 7 The Driving Effect of Environmental Factors on Algae Evolution 7.1 The influence of marine chemistry and climate change on lineage evolution Global marine chemistry (such as nutrients, pH, dissolved oxygen) and climate change have far-reaching effects on algae evolution. In ancient marine history, warming or cooling climates and the arrival of glaciers will change light and nutritional conditions, thereby screening and driving changes in algae community structure. During the period of increasing atmospheric carbon dioxide, the photosynthesis of algae increases, which promotes the expansion of photosynthetic groups; while the increase in oxygen content brings new ecological niches to aerobic algae (Zhou et al., 2022). In addition, ocean acidification can affect the calcium carbonate structure of algae (such as some dinoflagellates and seaweed), changing the basis of the food web. Modern marine environmental studies have shown that algae can exhibit variable adaptive responses to nutrient enrichment (eutrophication) and rising seawater temperatures, but these environmental pressures may also accelerate the emergence of certain harmful algae bloom taxa (Cabrera et al., 2019). Therefore, marine environmental chemistry and climate change continue to shape the evolutionary paths of algae lineages on different time scales. 7.2 Adaptive response to water transparency, temperature and nutrient changes The differences in light conditions, temperature gradients and nutrient content in freshwater and marine ecosystems play an important driving role in the diversification of algae. In shallow water transparent environments, blue-green light-rich light-rich is conducive to the growth of cyanobacteria and red algae containing phycobilin (Gordillo, 2012); in turbid and nutritious water bodies, green algae and some diatoms show stronger competitiveness. Under high temperature environment, some tropical seaweeds (such as brown algae) can adapt to heat stress by accumulating heat shock proteins and changing cell membrane composition; while under low temperature conditions, Antarctic algae (such as ice green algae) maintain photosynthetic ability by accumulating antifreeze proteins and adjusting lipid ratios (Il’ichev and Il’icheva, 2021). These environmental gradients prompted the algae to evolve specific physiological strategies, such as changing pigment ratios to adapt to light, enhancing competitiveness for nutrients, etc., to fill the ecological niches in different habitats. In addition, the interoperability and breakage of freshwater and seawater environment also causes some algae groups to evolve independently, forming different lineages of freshwater algae and seawater algae.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==